Method and device for transmitting signal in wireless communication system

ABSTRACT

The present invention relates to a wireless communication system. Specifically, the present invention relates to a method for transmitting, by a terminal, an HARQ-ACK in a CA wireless communication system and a device therefor, the method comprising the steps of: receiving a first PDCCH including a first DAI and a second DAI within SF #n-k; configuring an HARQACK payload using the first DAI and the second DAI; and transmitting the HARQ-ACK payload in SF on, wherein the value of the first DAI indicates the order values of scheduling of cell/SF units associated with the first PDCCH in SF #n-k, the order values of scheduling of cell/SF units are counted in a manner in which priority is given to cells in the cell/SF domain, and the value of the second DAI corresponds to a value obtained by accumulating the numbers of cells scheduled for the terminal by a DG DCI in each SF from the first SF to the SF, in which the first PDCCH is received, within SF #n-k (k#K).

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly to a method and apparatus for transmitting/receivingsignals. The wireless communication system can support a carrieraggregation (CA).

BACKGROUND ART

Wireless communication systems have been widely used to provide variouskinds of communication services such as voice or data services.Generally, a wireless communication system is a multiple access systemthat can communicate with multiple users by sharing available systemresources (bandwidth, transmission (Tx) power, and the like). A varietyof multiple access systems can be used. For example, a Code DivisionMultiple Access (CDMA) system, a Frequency Division Multiple Access(FDMA) system, a Time Division Multiple Access (TDMA) system, anOrthogonal Frequency Division Multiple Access (OFDMA) system, a SingleCarrier Frequency-Division Multiple Access (SC-FDMA) system, and thelike.

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies ina method and apparatus for efficiently transmitting signals in awireless communication system. Another object of the present inventiondevised to solve the problem lies in a method and apparatus forefficiently controlling transmission of uplink signals.

It is to be understood that technical objects to be achieved by thepresent invention are not limited to the aforementioned technicalobjects and other technical objects which are not mentioned herein willbe apparent from the following description to one of ordinary skill inthe art to which the present invention pertains.

Technical Solution

In one aspect of the present invention, provided herein is a method fortransmitting a hybrid automatic repeat request (HARQ-ACK) by a userequipment (UE) in a carrier aggregation (CA) wireless communicationsystem, the method including receiving a first physical downlink controlchannel (PDCCH) including a downlink assignment index (DAI) and a secondDAI in subframe (SF) #n-k, configuring an HARQ-ACK payload using thefirst DAI and the second DAI, and transmitting the HARQ-ACK payload inSF #n, wherein a value of the first DAI indicates a scheduling ordervalue in units of cell/SF associated with the first PDCCH in SF #n-k,the scheduling order value in units of cell/SF being counted in a cellprioritized manner, wherein a value of the second DAI corresponds to avalue obtained by accumulating, from a first SF to an SF in which thefirst PDCCH is received within SF #n-k (kEK), the number of cellsscheduled for the UE in each SF by downlink grant (DG) downlink controlinformation (DCI), wherein K: {k₀, k₁, . . . k_(M−1)} in each cell isgiven as follows:

TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6— 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — —3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — —— — 5 — — 13, 12, 9, 8, 7, 5, 4, — — — — — — — 11, 6 6 — — 7 7 5 — — 7 7 —.

In another aspect of the present invention, provided herein is a userequipment (UE) configured to transmit a hybrid automatic repeat request(HARQ-ACK) in a carrier aggregation (CA) wireless communication system,the UE including a radio frequency (RF) unit, and a processor, whereinthe processor is configured to receive a first physical downlink controlchannel (PDCCH) including a downlink assignment index (DAI) and a secondDAI in subframe (SF) #n-k, configure an HARQ-ACK payload using the firstDAI and the second DAI, and transmit the HARQ-ACK payload in SF #n,wherein a value of the first DAI indicates a scheduling order value inunits of cell/SF associated with the first PDCCH in SF #n-k, thescheduling order value in units of cell/SF being counted in a cellprioritized manner, wherein a value of the second DAI corresponds to avalue obtained by accumulating, from a first SF to an SF in which thefirst PDCCH is received within SF #n-k (kEK), the number of cellsscheduled for the UE in each SF by downlink grant (DG) downlink controlinformation (DCI), wherein K: {k₀, k₁, . . . k_(M−1)} is given asfollows:

TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6— 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — —3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — —— — 5 — — 13, 12, 9, 8, 7, 5, 4, — — — — — — — 11, 6 6 — — 7 7 5 — — 7 7 —.

Preferably, the first PDCCH may be received in a UE-specific searchspace (USS) of SF #n-k.

Preferably, the method may further include receiving a second PDCCH in acommon search space (CSS) of SF #n-k, wherein the second PDCCH may notcontain the second DAI.

Preferably, the first PDCCH may be (i) a PDCCH for scheduling a physicaldownlink shared channel (PDSCH) or (ii) a PDCCH indicating asemi-persistent scheduling release (SPS release).

Preferably, the HARQ-ACK payload may include an HARQ-ACK response to thePDSCH or an HARQ-ACK response to the PDCCH indicating the SPS release.

Advantageous Effects

As is apparent from the above description, exemplary embodiments of thepresent invention can provide a method and apparatus for efficientlytransmitting signals in a wireless communication system. In more detail,the embodiments of the present invention efficiently can controltransmission of uplink signals.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present invention are not limited to whathas been particularly described hereinabove and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

FIG. 1 is a conceptual diagram illustrating physical channels used in a3GPP LTE system acting as an exemplary mobile communication system and ageneral method for transmitting a signal using the physical channels.

FIG. 2 is a diagram illustrating a structure of a radio frame.

FIG. 3 exemplarily shows a resource grid of a downlink slot.

FIG. 4 illustrates a downlink frame structure.

FIG. 5 illustrates an uplink subframe structure.

FIG. 6 shows an example for deciding PUCCH resources for ACK/NACK.

FIGS. 7-8 show a TDD Uplink Acknowledgement/Negative Acknowledgement (ULACK/NACK) transmission timing in a single cell situation.

FIG. 9 illustrates an ACK/NACK transmission using Downlink AssignmentIndex (DAI).

FIG. 10 exemplarily shows a carrier aggregation (CA) communicationsystem.

FIG. 11 exemplarily shows cross-carrier scheduling when a plurality ofcarriers are aggregated.

FIGS. 12˜13 show an example of PUCCH format 3.

FIG. 14 is a conceptual diagram illustrating that control informationand UL-SCH data are multiplexed on a Physical Uplink Shared CHannel(PUSCH).

FIG. 15 shows an example of constructing an ACK/NACK payload in aconventional TDD CA.

FIGS. 16˜19 exemplarily show a method for allocating DAI according toembodiments of the present invention.

FIG. 20 exemplarily shows a Base Station (BS) and a user equipment (UE)applicable to the embodiments of the present invention.

BEST MODE

Reference will now be made in detail to the preferred embodiments of thepresent invention with reference to the accompanying drawings. Thedetailed description, which will be given below with reference to theaccompanying drawings, is intended to explain exemplary embodiments ofthe present invention, rather than to show the only embodiments that canbe implemented according to the invention. The following embodiments ofthe present invention can be applied to a variety of wireless accesstechnologies, for example, CDMA, FDMA, TDMA, OFDMA, SC-FDMA, MC-FDMA,and the like. CDMA can be implemented by wireless communicationtechnologies, such as Universal Terrestrial Radio Access (UTRA) orCDMA2000. TDMA can be implemented by wireless communicationtechnologies, for example, a Global System for Mobile communications(GSM), a General Packet Radio Service (GPRS), an Enhanced Data rates forGSM Evolution (EDGE), etc. OFDMA can be implemented by wirelesscommunication technologies, for example, IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802.20, E-UTRA (Evolved UTRA), and the like. UTRAis a part of a Universal Mobile Telecommunications System (UMTS). 3rdGeneration Partnership Project (3GPP) Long Term Evolution (LTE) is apart of an Evolved UMTS (E-UMTS) that uses an E-UTRA. The LTE-Advanced(LTE-A) is an evolved version of 3GPP LTE. Although the followingembodiments of the present invention will hereinafter describe inventivetechnical characteristics on the basis of the 3GPP LTE/LTE-A system, itshould be noted that the following embodiments will be disclosed onlyfor illustrative purposes and the scope and spirit of the presentinvention are not limited thereto.

In a wireless communication system, a UE receives information from a BSon downlink (DL) and transmits information to the BS on uplink (UL).Information transmitted/received between the UE and BS includes data andvarious types of control information, and various physical channels arepresent according to type/purpose of information transmitted/receivedbetween the UE and BS.

FIG. 1 illustrates physical channels used in a 3GPP LTE system and asignal transmission method using the same.

When powered on or when a UE initially enters a cell, the UE performsinitial cell search involving synchronization with a BS in step S101.For initial cell search, the UE synchronizes with the BS and acquireinformation such as a cell Identifier (ID) by receiving a primarysynchronization channel (P-SCH) and a secondary synchronization channel(S-SCH) from the BS. Then the UE may receive broadcast information fromthe cell on a physical broadcast channel (PBCH). In the meantime, the UEmay check a downlink channel status by receiving a downlink referencesignal (DL RS) during initial cell search.

After initial cell search, the UE may acquire more specific systeminformation by receiving a physical downlink control channel (PDCCH) andreceiving a physical downlink shared channel (PDSCH) based oninformation of the PDCCH in step S102.

The UE may perform a random access procedure to access the BS in stepsS103 to S106. For random access, the UE may transmit a preamble to theBS on a physical random access channel (PRACH) (S103) and receive aresponse message for preamble on a PDCCH and a PDSCH corresponding tothe PDCCH (S104). In the case of contention-based random access, the UEmay perform a contention resolution procedure by further transmittingthe PRACH (S105) and receiving a PDCCH and a PDSCH corresponding to thePDCCH (S106).

After the foregoing procedure, the UE may receive a PDCCH/PDSCH (S107)and transmit a physical uplink shared channel (PUSCH)/physical uplinkcontrol channel (PUCCH) (S108), as a general downlink/uplink signaltransmission procedure. Here, control information transmitted from theUE to the BS is called uplink control information (UCI). The UCI mayinclude a hybrid automatic repeat and request (HARQ)acknowledgement(ACK)/negative-ACK (HARQ ACK/NACK) signal, a schedulingrequest (SR), channel state information (CSI), etc. The CSI includes achannel quality indicator (CQI), a precoding matrix index (PMI), a rankindicator (RI), etc. While the UCI is transmitted through a PUCCH ingeneral, it may be transmitted through a PUSCH when control informationand traffic data need to be simultaneously transmitted. The UCI may beaperiodically transmitted through a PUSCH at the request/instruction ofa network.

FIG. 2 illustrates a radio frame structure. In a cellular OFDM wirelesspacket communication system, uplink/downlink data packet transmission isperformed on a subframe-by-subframe basis. A subframe is defined as apredetermined time interval including a plurality of OFDM symbols. 3GPPLTE supports a type-1 radio frame structure applicable to FDD (FrequencyDivision Duplex) and a type-2 radio frame structure applicable to TDD(Time Division Duplex).

FIG. 2(a) illustrates a type-1 radio frame structure. A downlinksubframe includes 10 subframes each of which includes 2 slots in thetime domain. A time for transmitting a subframe is defined as atransmission time interval (TTI). For example, each subframe has alength of 1 ms and each slot has a length of 0.5 ms. A slot includes aplurality of OFDM symbols in the time domain and includes a plurality ofresource blocks (RBs) in the frequency domain. Since downlink uses OFDMin 3GPP LTE, an OFDM symbol represents a symbol period. The OFDM symbolmay be called an SC-FDMA symbol or symbol period. An RB as a resourceallocation unit may include a plurality of consecutive subcarriers inone slot.

The number of OFDM symbols included in one slot may depend on CyclicPrefix (CP) configuration. CPs include an extended CP and a normal CP.When an OFDM symbol is configured with the normal CP, for example, thenumber of OFDM symbols included in one slot may be 7. When an OFDMsymbol is configured with the extended CP, the length of one OFDM symbolincreases, and thus the number of OFDM symbols included in one slot issmaller than that in case of the normal CP. In case of the extended CP,the number of OFDM symbols allocated to one slot may be 6. When achannel state is unstable, such as a case in which a UE moves at a highspeed, the extended CP can be used to reduce inter-symbol interference.

When the normal CP is used, one subframe includes 14 OFDM symbols sinceone slot has 7 OFDM symbols. The first three OFDM symbols at most ineach subframe can be allocated to a PDCCH and the remaining OFDM symbolscan be allocated to a PDSCH.

FIG. 2(b) illustrates a type-2 radio frame structure. The type-2 radioframe includes 2 half frames. Each half frame includes 4(5) normalsubframes and 1(0) special subframe. Normal subframes are used for anuplink or a downlink according to UL-DL configuration. A subframeincludes 2 slots.

Table 1 shows subframe configurations in a radio frame according toUL-DL configuration.

TABLE 1 Uplink- Downlink- downlink to-Uplink config- Switch-pointSubframe number uration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U UD S U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms D S U U U D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D DD D D 6 5 ms D S U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes DwPTS(Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS (Uplink PilotTimeSlot). DwPTS is used for initial cell search, synchronization orchannel estimation in a UE. UpPTS is used for channel estimation in a BSand UL transmission synchronization acquisition in a UE. The GPeliminates UL interference caused by multi-path delay of a DL signalbetween a UL and a DL.

The radio frame structure is merely exemplary and the number ofsubframes included in the radio frame, the number of slots included in asubframe, and the number of symbols included in a slot can be vary.

FIG. 3 illustrates a resource grid of a downlink slot.

Referring to FIG. 3, a downlink slot includes a plurality of OFDMsymbols in the time domain. One downlink slot may include 7 OFDMsymbols, and one resource block (RB) may include 12 subcarriers in thefrequency domain. However, the present invention is not limited thereto.Each element on the resource grid is referred to as a resource element(RE). One RB includes 12×7 REs. The number N^(DL) of RBs included in thedownlink slot depends on a downlink transmit bandwidth. The structure ofan uplink slot may be same as that of the downlink slot.

FIG. 4 illustrates a downlink subframe structure.

Referring to FIG. 4, a maximum of three (four) OFDM symbols located in afront portion of a first slot within a subframe correspond to a controlregion to which a control channel is allocated. The remaining OFDMsymbols correspond to a data region to which a physical downlink sharedchancel (PDSCH) is allocated. Examples of downlink control channels usedin LTE include a physical control format indicator channel (PCFICH), aphysical downlink control channel (PDCCH), a physical hybrid ARQindicator channel (PHICH), etc. The PCFICH is transmitted at a firstOFDM symbol of a subframe and carries information regarding the numberof OFDM symbols used for transmission of control channels within thesubframe. The PHICH is a response of uplink transmission and carries anHARQ acknowledgment (ACK)/negative-acknowledgment (NACK) signal. Controlinformation transmitted through the PDCCH is referred to as downlinkcontrol information (DCI). The DCI includes uplink or downlinkscheduling information or an uplink transmit power control command foran arbitrary UIE group.

Control information transmitted through a PDCCH is referred to as DCI.Formats 0, 3, 3A and 4 for uplink and formats 1, 1A, 1B, 1C, 1D, 2, 2A,2B and 2C for downlink are defined as DCI formats. Information fieldtypes, the number of information fields and the number of bits of eachinformation field depend on DCI format. For example, the DCI formatsselectively include information such as hopping flag, RB allocation, MCS(modulation coding scheme), RV (redundancy version), NDI (new dataindicator), TPC (transmit power control), HARQ process number, PMI(precoding matrix indicator) confirmation as necessary. A DCI format canbe used to transmit control information of two or more types. Forexample, DCI format 0/1A is used to carry DCI format 0 or DCI format 1,which are discriminated from each other by a flag field.

A PDCCH may carry a transport format and a resource allocation of adownlink shared channel (DL-SCH), resource allocation information of anuplink shared channel (UL-SCH), paging information on a paging channel(PCH), system information on the DL-SCH, information on resourceallocation of an upper-layer control message such as a random accessresponse transmitted on the PDSCH, a set of Tx power control commands onindividual UEs within an arbitrary UE group, a Tx power control command,information on activation of a voice over IP (VoIP), etc. A plurality ofPDCCHs can be transmitted within a control region. The UE can monitorthe plurality of PDCCHs. The PDCCH is transmitted on an aggregation ofone or several consecutive control channel elements (CCEs). The CCE is alogical allocation unit used to provide the PDCCH with a coding ratebased on a state of a radio channel. The CCE corresponds to a pluralityof resource element groups (REGs). A format of the PDCCH and the numberof bits of the available PDCCH are determined by the number of CCEs. TheBS determines a PDCCH format according to DCI to be transmitted to theUE, and attaches a cyclic redundancy check (CRC) to control information.The CRC is masked with a unique identifier (referred to as a radionetwork temporary identifier (RNTI)) according to an owner or usage ofthe PDCCH. If the PDCCH is for a specific UE, a unique identifier (e.g.,cell-RNTI (C-RNTI)) of the UE may be masked to the CRC. Alternatively,if the PDCCH is for a paging message, a paging identifier (e.g.,paging-RNTI (P-RNTI)) may be masked to the CRC. If the PDCCH is forsystem information (more specifically, a system information block(SIB)), a system information RNTI (SI-RNTI) may be masked to the CRC.When the PDCCH is for a random access response, a random access-RNTI(RA-RNTI) may be masked to the CRC.

The PDCCH carries a message known as DCI, and generally, a plurality ofPDCCHs is transmitted in a subframe. Each PDCCH is transmitted using oneor more CCEs. One CCE corresponds to nine REGs, and one REG correspondsto four REs. Four QPSK symbols are mapped to each REG. The resourceelement occupied by the reference signal is not included in the REG.Thus, the number of REGs within a given OFDM symbol depends on thepresence or absence of a cell-specific reference signal. The REG conceptis also used for other downlink control channels (i.e., PDFICH andPHICH). As shown in Table 2, four PDCCH formats are supported.

TABLE 2 Number Number PDCCH of CCEs Number of PDCCH format (n) of REGsbits 0 1 9 72 1 2 18 144 2 4 36 288 3 8 72 576

The CCEs are numbered and consecutively used. To simplify the decodingprocess, a PDCCH having a format including n CCEs may be initiated onlyon CCEs assigned numbers corresponding to multiples of n. The number ofCCEs used for transmission of a specific PDCCH is determined by the BSaccording to the channel state. For example, one CCE may be required fora PDCCH for a UE (for example, adjacent to the BS) having a gooddownlink channel. However, in case of a PDCCH for a UE (for example,located near the cell edge) having a poor channel, eight CCEs may berequired to obtain sufficient robustness. Additionally, the power levelof the PDCCH may be adjusted according to the channel state.

In LTE, a set of CCEs on which a PDCCH can be located for each UE isdefined. A CCE set in which the UE can detect a PDCCH thereof isreferred to as a PDCCH search space or simply as a search space (SS). Anindividual resource on which the PDCCH can be transmitted in the SS iscalled a PDCCH candidate. One PDCCH candidate corresponds to 1, 2, 4 or8 CCEs according to the CCE set level. The BS transmits an actual PDCCH(DCI) on a PDCCH candidate in a search space and the UE monitors thesearch space to detect the PDCCH (DCI). Specifically, the UE attemptsblind decoding (BD) on the PDCCH candidates in the search space.

In LTE, SSs for respective PDCCH formats may have different sizes. Adedicated SS and a common SS are defined. A dedicated SS (or UE-specificSS (USS)) and a common SS (Common SS (CSS)) are defined. The dedicatedsearch space is configured for each individual UE, and all UEs areprovided with information about the range of the common SS. Thededicated SS and the common SS may overlap for a given UE.

Since the SSs are small in size and may overlap each other, the basestation may not be able to find a CCE resource for sending a PDCCH toall desired UEs in a given subframe. This is because CCE resources havealready been allocated to other UEs, and there may be no more CCEresources for a specific UE in the search space of the specific UE(blocking). In order to minimize the possibility of blocking to becontinued in the next subframe, a UE-specific hopping sequence isapplied to the start position of the dedicated SS. Table 3 shows thesizes of common and dedicated SSs.

TABLE 3 Number of Number of Number candidates candidates PDCCH of CCEsin common in dedicated format (n) search space search space 0 1 — 6 1 1— 6 2 4 4 2 3 8 2 2

To put the computational load according to attempts of blind decodingunder control, the UE does not simultaneously search all defined DCIformats. In general, in a dedicated search space, the UE always searchesformats 0 and 1A. Formats 0 and 1A have the same size and aredistinguished by flags in the message. In addition, the UE may befurther required to receive another format (i.e., format 1, 1B or 2depending on the PDSCH transmission mode set by the base station). Inthe common search space, the UE searches formats 1A and 1C. In addition,the UE may be configured to search format 3 or 3A. Formats 3 and 3A havethe same size as in the case of format 0/1A, and are distinguishedaccording to whether they have a CRC scrambled with another (common)identifier. Transmission modes and information content of DCI formatsfor configuring a multi-antenna technology are as follows.

Transmission Mode (TM)

-   -   Transmission mode 1: Transmission from a single base station        antenna port    -   Transmission mode 2: Transmit diversity    -   Transmission mode 3: Open-loop spatial multiplexing    -   Transmission mode 4: Closed-loop spatial multiplexing    -   Transmission mode 5: Multi-user MIMO    -   Transmission mode 6: Closed-loop rank-1 precoding    -   Transmission mode 7: Transmission using UE-specific reference        signals

DCI Format

-   -   Format 0: Resource grants for the PUSCH transmissions (uplink)    -   Format 1: Resource assignments for single codeword PDSCH        transmissions (transmission modes 1, 2 and 7)    -   Format 1A: Compact signaling of resource assignments for single        codeword PDSCH (all modes)    -   Format 1B: Compact resource assignments for PDSCH using rank-1        closed loop precoding (mod 6)    -   Format 1C: Very compact resource assignments for PDSCH (e.g.        paging/broadcast system information)    -   Format 1D: Compact resource assignments for PDSCH using        multi-user MIMO (mode 5)    -   Format 2: Resource assignments for PDSCH for closed-loop MIMO        operation (mode 4)    -   Format 2A: Resource assignments for PDSCH for open-loop MIMO        operation (mode 3)    -   Format 3/3A: Power control commands for PUCCH and PUSCH with        2-bit/1-bit power adjustments

FIG. 5 illustrates an uplink subframe structure used in LTE.

Referring to FIG. 5, a subframe 500 includes two 0.5 ms slots 501. Whena normal CP is used, each slot includes 7 symbols 502 each correspondingto an SC-FDMA symbol. A resource block 503 is a resource allocation unitcorresponding to 12 subcarriers in the frequency domain and to a slot inthe time domain. The uplink subframe is divided into a data region 504and a control region 505. The data region refers to a communicationresource used for a UE to transmit data such as audio data, packets,etc. and includes a PUSCH (physical uplink shared channel). The controlregion refers to a communication resource used for the UE to transmituplink control information (UCI) and includes a PUCCH (physical uplinkcontrol channel).

The PUCCH can be used to transmit the following control information.

-   -   SR (scheduling request): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ ACK: This is a response to a downlink data packet (e.g.        codeword) on a PDSCH and indicates whether the downlink data        packet has been successfully received. A 1-bit ACK/NACK signal        is transmitted as a response to a single downlink codeword and a        2-bit ACK/NACK signal is transmitted as a response to two        downlink codewords. A HARQ-ACK response includes positive ACK        (simply, ACK), negative ACK (NACK), DTX or NACK/DTX. Here,        HARQ-ACK is used interchangeably with HARQ ACK/NACK and        ACK/NACK.    -   CSI (channel state information): This is feedback information        about a downlink channel. Feedback information regarding        multiple input multiple output (MIMO) includes rank indicator        (RI) and precoding matrix index (PMI). 20 bits are used for each        subframe.

The quantity of control information that a UE can transmit through asubframe depends on the number of SC-FDMA symbols available for controlinformation transmission. The SC-FDMA symbols available for controlinformation transmission correspond to SC-FDMA symbols other thanSC-FDMA symbols of the subframe, which are used for reference signaltransmission. In the case of a subframe in which a sounding referencesignal (SRS) is configured, the last SC-FDMA symbol of the subframe isexcluded from the SC-FDMA symbols available for control informationtransmission. A reference signal is used to detect coherence of thePUCCH. The PUCCH supports various formats according to informationtransmitted thereon.

Table 4 shows the mapping relationship between PUCCH formats and UCI inLTE(-A).

TABLE 4 PUCCH format UCI (Uplink Control Information) Format 1 SR(Scheduling Request) (non-modulated waveform Format 1a 1-bit HARQACK/NACK (SR exist/non-exist) Format 1b 2-bit HARQ ACK/NACK (SRexist/non-exist) Format 2 CQI (20 coded bits) Format 2 CQI and 1- or2-bit HARQ ACK/NACK (20 bits) (corresponding to only extended CP) Format2a CQI and 1-bit HARQ ACK/NACK (20 + 1 coded bits) Format 2b CQI and2-bit HARQ ACK/NACK (20 + 2 coded bits) Format 3 Up to 24-bit HARQACK/NACK + SR (LTE-A)

An SRS is transmitted through the last SC-FDMA symbol of the subframe(506). SRSs of multiple UEs, transmitted through the same SC-FDMAsymbol, can be discriminated according to frequency position/sequence.The SRS is transmitted aperiodically or periodically.

FIG. 6 shows an example for deciding PUCCH resources for ACK/NACK. Inthe LTE system, PUCCH resources for ACK/NACK are not pre-allocated toeach UE, and several UEs located in the cell are configured todivisionally use several PUCCH resources at every time point. In moredetail, PUCCH resources used for ACK/NACK transmission of a UE maycorrespond to a PDCCH that carries scheduling information of thecorresponding DL data. The entire region to which a PDCCH is transmittedin each DL subframe is comprised of a plurality of Control ChannelElements (CCEs), and a PDCCH transmitted to the UE is comprised of oneor more CCEs. The UE may transmit ACK/NACK through PUCCH resources(e.g., first CCE) from among CCEs constructing a PDCCH received by theUE.

Referring to FIG. 6, each block in a Downlink Component Carrier (DL CC)represents a CCE and each block in an Uplink Component Carrier (UL CC)indicates a PUCCH resource. Each PUCCH resource index may correspond toa PUCCH resource for an ACK/NACK signal. If information on a PDSCH isdelivered on a PDCCH composed of CCEs #4˜#6, as shown in FIG. 6, a UEtransmits an ACK/NACK signal on PUCCH #4 corresponding to CCE #4, thefirst CCE of the PDCCH. FIG. 6 illustrates a case in which a maximum ofM PUCCHs are present in the UL CC when a maximum of N CCEs exist in theDL CC. Though N may be identical to M (M=M), N may differ from M andCCEs may be mapped to PUCCHs in an overlapped manner.

Specifically, a PUCCH resource index in an LTE system is determined asfollows.

n ⁽¹⁾ _(PUCCH) =n _(CCE) +N ⁽¹⁾ _(PUCCH)  [Equation 1]

Here, n⁽¹⁾ _(PUCCH) represents a resource index of PUCCH format 1 forACK/NACK/DTX transmission, N⁽¹⁾ _(PUCCH) denotes a signaling valuereceived from a higher layer, and n_(CCE) denotes the smallest value ofCCE indexes used for PDCCH transmission. A cyclic shift (CS), anorthogonal spreading code and a Physical Resource Block (PRB) for PUCCHformats 1a/1b are obtained from n⁽¹⁾ _(PUCCH).

A description will be given of TDD signal transmission timing in asingle carrier (or cell) situation with reference to FIGS. 7 to 8.

FIGS. 7-8 illustrate PDSCH-UL ACK/NACK timing. Here, UL ACK/NACK meansACK/NACK transmitted on uplink, as a response to DL data (e.g. PDSCH).

Referring to FIG. 7, a UE can receive one or more PDSCH signals in M DLsubframes (SFs) (S502_0 to S502_M−1). Each PDSCH signal is used totransmit one or more (e.g. 2) transport blocks (TBs) according totransmission mode. A PDCCH signal indicating SPS (Semi-PersistentScheduling) may also be received in step S502_0 to S502_M−1, which isnot shown. When a PDSCH signal and/or an SPS release PDCCH signal ispresent in the M DL subframes, the UE transmits ACK/NACK through a ULsubframe corresponding to the M DL subframes via processes fortransmitting ACK/NACK (e.g. ACK/NACK (payload) generation, ACK/NACKresource allocation, etc.) (S504). ACK/NACK includes acknowledgementinformation about the PDSCH signal and/or an SPS release PDCCH receivedin step S502_0 to S502_M−1. While ACK/NACK is transmitted through aPUCCH basically, ACK/NACK is transmitted through a PUSCH when a PUSCH istransmitted at ACK/NACK transmission time. Various PUCCH formats shownin Table 4 can be used for ACK/NACK transmission. To reduce the numberof ACK/NACK bits transmitted through a PUCCH format, various methodssuch as ACK/NACK bundling and ACK/NACK channel selection can be used.

As described above, in TDD, ACK/NACK relating to data received in the MDL subframes is transmitted through one UL subframe (i.e. M DL SF(s):1UL SF) and the relationship therebetween is determined by a DASI(Downlink Association Set Index).

Table 5 shows DASI (K: {k₀, k₁, . . . , k_(M−1)}) defined in LTE(-A).Table 3 shows spacing between a UL subframe transmitting ACK/NACK and aDL subframe relating to the UL subframe. Specifically, when a PDCCH thatindicates PDSCH transmission and/or SPS release is present in a subframen-k (k∈K), the UE transmits ACK/NACK in a subframe n.

TABLE 5 TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 —4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7,4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4,7 — — — — — — 5 — — 13, 12, 9, 5, 4, — — — — — — — 8, 7, 11, 6 6 — — 7 75 — — 7 7 —

FIG. 8 illustrates UL ACK/NACK transmission timing when UL-DLconfiguration #1 is configured. In the figure, SF #0 to #9 and SF #10 to#19 respectively correspond to radio frames, and numerals in blocksdenote UL subframes relating to DL subframes. For example, ACK/NACK fora PDSCH of SF #5 is transmitted in SF #5+7 (=SF #12) and ACK/NACK for aPDSCH of SF #6 is transmitted in SF #6+6 (=SF #12). Accordingly, bothACKs/NACKs for DL signals of SF #5/#6 are transmitted in SF #12.Similarly, ACK/NACK for a PDSCH of SF #14 is transmitted in SF #14+4(=SF #18).

When a UE transmits an ACK/NACK signal to a BS according to the TDDscheme, the following problems may occur.

-   -   If a UE misses at least one of PDCCH(s) transmitted from a BS        during an interval of subframes, the UE does not even recognize        whether a PDSCH corresponding to the missing PDCCH is        transmitted to the UE, resulting in the occurrence of errors in        ACK/NACK generation.

In order to solve the above-mentioned errors, the TDD system includes adownlink assignment index (DAI) in a PDCCH. DAI indicates anaccumulative value (i.e., a counting value) of PDCCH(s) corresponding toPDSCH(s) and PDCCH(s) indicating DL SPS release up to a current subframewithin DL subframe(s) n-k (k∈K). For example, if three DL subframes aremapped to one UL subframe, PDSCHs transmitted in 3 DL subframe intervalsare sequentially indexed (i.e., sequentially counted), and the indexedresult is loaded on a PDCCH that schedules a PDSCH. As a result, the UEcan recognize whether a PDCCH has been normally received on the basis ofDAI information contained in the PDCCH.

FIG. 9 exemplarily shows ACK/NACK transmission using a DAI. For example,according to the TDD system shown in FIG. 9, one UL subframe is mappedto three DL subframes (i.e., 3 DL subframes:1 UL subframe). Forconvenience of description, it is assumed that the UE transmits anACK/NACK signal using a PUCCH resource corresponding to the lastdetected PDCCH.

The first example of FIG. 9 shows that a UE missed a second PDCCH. Sincea DAI value (DAI=3) of a third PDCCH is different from the number (i.e.,2) of received PDCCHs, the UE recognizes that the second PDCCH has beenmissed. In this case, the UE transmits ACK/NACK information using PUCCHresources corresponding to DAI=3, and an ACK/NACK response to the secondPDCCH may be indicated by NACK (or NACK/DTX). In contrast, if the UE hasmissed the last PDCCH as shown in the second example, the UE is unableto recognize the absence (i.e., missing) of the last PDCCH because a DAIindex of the last received PDCCH is identical to the number of receivedPDCCHs. Therefore, the UE recognizes that only two PDCCHs have beenscheduled during the DL subframe. The UE transmits ACK/NACK informationusing PUCCH resources corresponding to DAI=2, such that the BS canrecognize absence of a PDCCH including DAI=3.

FIG. 10 exemplarily shows a carrier aggregation (CA) communicationsystem. The LTE-A system is designed to use a carrier aggregation orbandwidth aggregation technique using a plurality of UL/DL frequencyblocks so as to use a wider frequency band. Each frequency block istransmitted using a component carrier (CC). The CC may be regarded as acarrier frequency (or center carrier, center frequency) for thefrequency block.

Referring to FIG. 10, a plurality of UL/DL CCs can be aggregated tosupport a wider UL/DL bandwidth. The CCs may be contiguous ornon-contiguous in the frequency domain. Bandwidths of the CCs can beindependently determined. Asymmetrical CA in which the number of UL CCsis different from the number of DL CCs can be implemented. For example,when there are two DL CCs and one UL CC, the DL CCs can correspond tothe UL CC in the ratio of 2:1. A DL CC/UL CC link can be fixed orsemi-statically configured in the system. Even if the system bandwidthis configured with N CCs, a frequency band that a specific UE canmonitor/receive can be limited to M (<N) CCs. Various parameters withrespect to CA can be set cell-specifically, UE-group-specifically, orUE-specifically. Control information may be transmitted/received onlythrough a specific CC. This specific CC can be referred to as a PrimaryCC (PCC) (or anchor CC) and other CCs can be referred to as SecondaryCCs (SCCs).

LTE-A uses the concept of a cell so as to manage radio resources. Thecell is defined as a combination of DL resources and UL resources. Here,the UL resources are not an essential part. Accordingly, the cell can beconfigured with DL resources only, or DL resources and UL resources.When CA is supported, the linkage between a carrier frequency (or DL CC)of a DL resource and a carrier frequency (or UL CC) of a UL resource canbe designated by system information. A cell operating at a primaryfrequency (or PCC) can be referred to as a Primary Cell (PCell) and acell operating at a secondary frequency (or SCC) can be referred to as aSecondary Cell (SCell). The PCell is used for a UE to perform an initialconnection establishment procedure or a connection re-establishmentprocedure. The PCell may refer to a cell designated during a handoverprocedure. The SCell can be configured after RRC connection isestablished and used to provide additional radio resources. The PCelland the SCell can be called a serving cell. Accordingly, for a UE thatdoes not support CA while in an RRC_connected state, only one servingcell configured with a PCell exists. Conversely, for a UE that is in anRRC_Connected state and supports CA, one or more serving cells includinga PCell and a SCell are provided. For CA, a network can configure one ormore SCells for a UE that supports CA in addition to a PCell initiallyconfigured during a connection establishment procedure after an initialsecurity activation procedure.

When cross-carrier scheduling (or cross-CC scheduling) is applied, aPDCCH for DL allocation can be transmitted through DL CC #0 and a PDSCHcorresponding thereto can be transmitted through DL CC #2. For cross-CCscheduling, introduction of a Carrier Indicator Field (CIF) may beconsidered. The presence or absence of a CIF in a PDCCH can be setsemi-statically and UE-specifically (or UE-group-specifically) accordingto higher layer signaling (e.g. RRC signaling). The base line of PDCCHtransmission is summarized as follows.

-   -   CIF disabled: PDCCH on a DL CC allocates a PDSCH resource on the        same DL CC or allocates a PUSCH resource on a linked UL CC.    -   CIF enabled: PDCCH on a DL CC can allocate a PDSCH or a PUSCH on        a specific UL/DL CC from among a plurality of aggregated DL/UL        CCs using the CIF.

When a CIF is present, a BS can allocate a PDCCH monitoring DL CC set inorder to reduce BD complexity of a UE. The PDCCH monitoring DL CC setincludes one or more DL CCs as part of aggregated DL CCs, and the UEdetects/decodes a PDCCH only on DL CCs corresponding to the DL CC set.That is, if the BS schedules PDSCH/PUSCH for the UE, the PDCCH istransmitted only through a PDCCH monitoring DL CC set. The PDCCHmonitoring DL CC set can be determined UE-specifically,UE-group-specifically or cell-specifically. The term “PDCCH monitoringDL CC” can be replaced by equivalent terms “monitoring carrier”,“monitoring cell”, etc. In addition, the term “aggregated CC” for a UEcan be replaced by terms “serving CC”, “serving carrier”, “servingcell”, etc.

FIG. 11 illustrates scheduling when a plurality of carriers isaggregated. It is assumed that 3 DL CCs are aggregated and DL CC A isset to a PDCCH monitoring DL CC. DL CC A, DL CC B and DL CC C can becalled serving CCs, serving carriers, serving cells, etc. In case of CIFdisabled, a DL CC can transmit only a PDCCH that schedules a PDSCHcorresponding to the DL CC without a CIF. When the CIF is enabledaccording to UE-specific (or UE-group-specific or cell-specific) higherlayer signaling, DL CC A (monitoring DL CC) can transmit not only aPDCCH that schedules the PDSCH corresponding to the DL CC A but alsoPDCCHs that schedule PDSCHs of other DL CCs. In this case, DL CC B andDL CC C that are not set to a PDCCH monitoring DL CCs do not deliverPDCCHs.

LTE-A considers transmission of a plurality of ACK/NACKinformation/signals with respect to a plurality of PDSCHs, which aretransmitted through a plurality of DL CCs, through a specific UL CC. Toachieve this, it can be considered to joint-code (Reed-Muller code,Tail-biting convolutional code, etc.) a plurality of ACK/NACKs andtransmit a plurality of ACK/NACK information/signals using PUCCH format2, or a new PUCCH format (referred to as an Enhanced PUCCH (E-PUCCH) orPUCCH format M), distinguished from ACK/NACK transmission using PUCCHformat 1a/1b in the legacy LTE system. The E-PUCCH format includes thefollowing block-spreading based PUCCH format. After joint coding,ACK/NACK transmission using E-PUCCH format is exemplary, and E-PUCCHformat may be used without being limited to UCI transmission. Forexample, E-PUCCH format may be used to transmit ACK/NACK, CSI (e.g. CQI,PMI, RI, PTI, etc.), SR, or two or more thereof. Accordingly, E-PUCCHformat may be used to transmit joint-coded UCI codewords irrespective oftype/number/size of UCI.

FIG. 12 illustrates a slot level structure of PUCCH format 3. PUCCHformat 3 is used to transmit a plurality of ACK/NACK information/signalsfor a plurality of PDSCHs transmitted through a plurality of DL CCs.PUCCH format 3 may be used to transmit ACK/NACK, CSI (e.g., CQI, PMI,RI, PTI, etc.), SR, or two or more of these information items together.

Referring to FIG. 12, five SC-FDMA symbols (i.e., a UCI data part) aregenerated from one symbol sequence ({d1, d2, . . . ) using OCC (C1 toC5) of length −5 (SF (Spreading Factor)=5). The symbol sequence {d1, d2,. . . ) may refer to a modulation symbol sequence or a codeword bitsequence. When the symbol sequence ({d1, d2, . . . ) refers to acodeword bit sequence, the block diagram of FIG. 12 further includes amodulation block. The RS symbol may be generated from a CAZAC sequencehaving a specific cyclic shift. The RS may be transmitted in a form inwhich a specific OCC is applied to (multiplied by) a plurality of RSsymbols in the time domain. The block-spread UCI is transmitted to thenetwork through an FFT (Fast Fourier Transform) process and an IFFT(Inverse Fast Fourier Transform) process on an SC-FDMA symbol basis.

FIG. 13 illustrates a subframe-level structure of a PUCCH format 3.Referring to FIG. 13, in slot 0, symbol sequence {d′0, d′1, . . . ,d′11} is mapped to a subcarrier of one SC-FDMA symbol and mapped to 5SC-FDMA symbols according to block spreading using OCC C1 to C5.Similarly, in slot 1, a symbol sequence {d′12, d′13, . . . , d′23} ismapped to a subcarrier of one SC-FDMA symbol and mapped to 5 SC-FDMAsymbols according to block-spreading using OCC C1 to C5. Here, symbolsequences {d′0, d′1, d′11} and {d′12, d′13, d′23} in slots 0 and 1represent symbol sequence {d1, d2, . . . }, shown in FIG. 12, which hasbeen subjected to FFT or FFT/IFFT. The entire symbol sequence {d′0, d′1,. . . , d′23} is generated by joint-coding one or more UCIs. The OCC maybe changed based on slot and UCI data may be scrambled for each SC-FDMAsymbol.

PUCCH format 3 resources may be explicitly allocated. In more detail, aPUCCH resource set is configured by a higher layer (e.g., RRC), andPUCCH resources to be actually used may be indicated by an ACK/NACKResource Indicator (ARI) of the PDCCH.

Table 6 explicitly shows PUCCH resources for HARQ-ACK.

TABLE 6 Value of HARQ-ACK resource for PUCCH (ARI) n_(PUCCH) 00 FirstPUCCH resource value configured by higher layer 01 Second PUCCH resourcevalue configured by higher layer 10 Third PUCCH resource valueconfigured by higher layer 11 Fourth PUCCH resource value configured byhigher layer

ARI represents an ACK/NACK resource indicator. In Table 6, the higherlayer may include an RRC layer and an ARI value may be indicated by aPDCCH carrying a DL grant. For example, the ARI value may be designatedusing an SCell PDCCH and/or a Transmit Power Control (TPC) field of oneor more PCell PDCCHs that do not correspond to a DAI initial value.

PUCCH format 4 is a PUCCH format that supports UCI transmission with apayload size larger than PUCCH format 3. The structure of PUCCH format 4is basically the same as that of PUCCH format 3 except thatblock-spreading is not employed in PUCCH format 4. In addition, PUCCHformat 4 resources may also be explicitly given. Specifically, a PUCCHresource set may be configured by a higher layer (e.g., RRC), and thePUCCH resource to be actually used may be indicated using the ARI valueof the PDCCH.

In LTE-A, there are two methods of transmitting UCI and UL-SCH data atthe same time. The first method is to transmit the PUCCH and the PUSCHat the same time, and the second method is to multiplex the UCI in thePUSCH as in legacy LTE. Whether the PUCCH and the PUSCH are allowed tobe simultaneously transmitted may be set by a higher layer. Whensimultaneous transmission of PUCCH and PUSCH is enabled, the firstmethod is used. When simultaneous transmission of PUCCH and PUSCH isdisabled, the second method is used. The legacy LTE UEs cannot transmitPUCCH and PUSCH at the same time. Accordingly, when UCI (e.g., CQI/PMI,HARQ-ACK, RI, etc.) transmission is required in a subframe in which thePUSCH is transmitted, the method of multiplexing UCI in the PUSCH regionis used. For example, when HARQ-ACK is to be transmitted in a subframeto which PUSCH transmission is allocated, the UE multiplexes the UL-SCHdata and the HARQ-ACK before DFT-spreading, and transmits the controlinformation and the data together on the PUSCH.

FIG. 14 is a conceptual diagram illustrating that control informationand UL-SCH data are multiplexed on a PUSCH. When transmitting controlinformation in a subframe to which PUSCH transmission is allocated, theUE simultaneously multiplexes control information (UCI) and UL-SCH dataprior to DFT spreading. The control information (UCI) includes at leastone of CQI/PMI, HARQ ACK/NACK and RI. The number of REs used fortransmission of each of CQI/PMI, ACK/NACK and RI is dependent uponModulation and Coding Scheme (MCS) and offset values assigned for PUSCHtransmission. The offset values allow different coding rates accordingto control information, and are semi-statically established by an higherlayer (e.g., RRC) signal. UL-SCH data and control information are notmapped to the same RE. Control information is mapped to be contained intwo slots of the subframe.

Referring to FIG. 14, CQI and/or PMI (CQI/PMI) resources are located atthe beginning part of UL-SCH data resources, are sequentially mapped toall SC-FDMA symbols on one subcarrier, and are finally mapped in thenext subcarrier. CQI/PMI is mapped from left to right within eachsubcarrier (i.e., in the direction of increasing SC-FDMA symbol index).PUSCH data (UL-SCH data) is rate-matched in consideration of the amountof CQI/PMI resources (i.e., the number of encoded symbols). Themodulation order identical to that of UL-SCH data may be used inCQI/PMI. ACK/NACK is inserted into some resources of the SC-FDMA mappedto UL-SCH data through puncturing. ACK/NACK is located close to RS,fills the corresponding SC-FDMA symbol from bottom to top (i.e., in thedirection of increasing subcarrier index) within the SC-FDMA symbol. Incase of a normal CP, the SC-FDMA symbol for ACK/NACK is located atSC-FDMA symbols #2 and #5 in each slot as can be seen from FIG. 14.Irrespective of whether ACK/NACK is actually transmitted in a subframe,the coded RI is located next to the symbol for ACK/NACK.

In addition, control information (e.g., information about QPSKmodulation) may be scheduled in a manner that the control informationcan be transmitted over PUSCH without UL-SCH data. Control information(CQI/PMI, RI and/or ACK/NACK) is multiplexed before DFT spreading so asto retain low CM (Cubic Metric) single-carrier characteristics.Multiplexing of ACK/NACK, RI and CQI/PMI is similar to that of FIG. 14.The SC-FDMA symbol for ACK/NACK is located next to RS, and resourcesmapped to the CQI may be punctured. The number of REs for ACK/NACK andthe number of REs for RI are dependent upon reference MCS (CQI/PMI MCS)and offset parameter. The reference MCS is calculated on the basis ofCQI payload size and resource allocation. Channel coding and ratematching to implement control signaling having no UL-SCH data areidentical to those of the other control signaling having UL-SCH data.

FIG. 15 shows an example of constructing an ACK/NACK payload in aconventional TDD CA.

Referring to FIG. 15, the UE may adjust the total ACK/NACK payload sizeusing the UL DAI value. UL DAI represents the DAI included in the ULgrant (UG) DCI. That is, the UL DAI is included in the PDCCH forscheduling the PUSCH. Specifically, the UE may determine the size of anACK/NACK payload (in other words, an ACK/NACK part) for each DL CC,considering the UL DAI value and the transmission mode and bundling ofthe corresponding CC. The UE may also determine the location of eachACK/NACK in the per-CC ACK/NACK payload using the DL DAI value(s)received at each DL CC. DL DAI represents the DAI included in the DLgrant (DG) DCI. That is, the UL DAI is included in the PDCCH forscheduling the PDSCH or included in the PDCCH for instructing release ofthe DL SPS.

In more detail, it is assumed that the HARQ-ACK feedback bit for thec-th DL CC (or serving cell) is defined as o_(c,0) ^(ACK) o_(c,1)^(ACK), . . . , o_(c,O) _(c) _(ACK) ⁻¹ ^(ACK) (where c≥0). O_(c) ^(ACK)is the (i.e., size) of HARQ-ACK payload bits for the c-th DL CC. If atransmission mode for supporting single transmission block (TB)transmission is configured in the c-th DL CC or if the spatial bundlingis applied to the c-th DL CC, O_(c) ^(ACK) may be identical to B_(c)^(DL) as denoted by O_(c) ^(ACK)=B_(c) DL. In contrast, if atransmission mode for supporting transmission of multiple transmissionblocks (e.g., two TBs) is configured in the c-th DL CC or if no spatialbundling is applied to the c-th DL CC, O_(c) ^(ACK) may be identical to2B_(c) ^(DL) as denoted by O_(c) ^(ACK)=2B_(c) ^(DL). B_(c) ^(DL) is thenumber (i.e., maxPDCCHperCC) of DL subframes requiring ACK/NACK feedbackin the c-th DL CC. If HARQ-ACK is transmitted through a PUSCH scheduledby a PDCCH, maxPDCCHperCC may be indicated by the value of a UL-DAIfield. In accordance with this example, when deciding the‘maxPDCCHperCC’ value, the BS may further consider a SPS PDSCH (that is,maxPDCCHperCC=3). In contrast, if HARQ-ACK is transmitted through aPUCCH or a SPS PUSCH, maxPDCCHperCC is denoted by M (i.e.,mxPDCCHperCC=M).

If a transmission mode for supporting transmission of a singletransmission block is established in the c-th DL CC, or if spatialbundling is applied to the c-th DL CC, the position of each ACK/NACK inper-CC HARQ-ACK payload is given as o_(c,DAI(k)−1) ^(ACK). DAI(k)indicates a DL DAI value of the PDCCH detected at the DL subframe (n-k).In contrast, if a transmission mode for supporting transmission ofmultiple transmission blocks (e.g., two transmission blocks) isconfigured in the c-th DL CC and no spatial bundling is applied to thec-th DL CC, the position of each ACK/NACK in per-CC HARQ-ACK payload isdenoted by o_(c,2DAI(k)−1) ^(ACK) and o_(c,2DAI(k)−1) ^(ACK).o_(c,2DAI(k)−2) ^(ACK) is a HARQ-ACK for the codeword 0, ando_(c,2DAI(k)−1) ^(ACK) is a HARQ-ACK for the codeword 1.

On the other hand, according to Option C, if SPS PDSCH is present, aHARQ-ACK position for SPS PDSCH may be located at o_(c,O) _(c) _(ACK) ⁻¹^(ACK) in a HARQ-ACK payload for the corresponding CC. CC where the SPSPDSCH is present may be limited to a DL PCC.

Thereafter, the UE allows HARQ-ACK payload (i.e., HARQ-ACK part for eachCC) for multiple CCs to be sequentially concatenated with each otheraccording to the cell index. Preferably, the HARQ-ACK payload may beconcatenated with each other in ascending numerical order of cell index.The entire HARQ-ACK payload configured by concatenation can betransmitted through a PUCCH or PUSCH upon completion of signalprocessing (e.g., channel coding, modulation, scrambling, etc.).

Embodiment: ACK/NACK (A/N) Transmission in Enhanced CA (eCA)

As described with reference to FIG. 15, in the existing CA system basedon TDD, a plurality of HARQ-ACK feedbacks for DL data reception in aplurality of cells may be transmitted through one UL SF. In addition,the HARQ-ACK feedback corresponding to each cell may include a pluralityof HARQ-ACKs (A/N) for DL data reception in a specific DL SF set(hereinafter referred to as a bundling window) in a corresponding cell.In addition, in DL grant (DG) DCI for scheduling each cell, a countervalue indicating the scheduling order of the corresponding DL datawithin the bundling window of the corresponding cell may be transmittedthrough DAI (i.e., DL DAI), and a specific value selected from the basestation may also be transmitted in the UL grant (UG) DCI through DAI(i.e., UL DAI). Accordingly, the UE may arrange A/N bits in order of theDL DAI values when the A/N payloads (per cell) are configured on thePUCCH/PUSCH. In particular, for A/N transmission on the PUSCH, the A/Nfeedback size may be reduced by constructing a payload only for DL DAIvalues below UL DAI (for each cell considering the UL DAI as the maximumvalue of DL DAI).

In a next-generation system, CA for a larger number of cells (e.g., 32cells) is considered. In this case, the A/N feedback size for one UL SFmay greatly increase in proportion to the number of cells subject to CA.DL scheduling may not be performed for all cells subject to CA in eachSF even if the UE has CA set for many cells. In other words, when thereis not much DL traffic, DL scheduling may be performed only for aspecific part of the cells subject to CA. Therefore, it may be effectiveto reduce the total A/N feedback size by omittingconfiguration/transmission for the A/N corresponding to the unscheduledcells as much as possible in terms of A/N feedback transmissionperformance and UCI transmission resource overhead.

Hereinafter, a method for efficiently transmitting uplink controlinformation, preferably ACK/NACK (i.e., HARQ-ACK), when a plurality ofcells is aggregated for one UE.

For simplicity, it is assumed that, when a cell is set to the non-MIMOmode, at most one transport block (TB) (equivalent to a codeword) can betransmitted in subframe k of a corresponding cell. If the cell is set tothe MIMO mode, it is assumed that a maximum of m (e.g., two) transportblocks (or codewords) can be transmitted in SF #k of the correspondingcell. Whether or not the cell is set to the MIMO mode may be identifiedusing the transmission mode set by a higher layer. The number ofACK/NACKs (i.e., ACK/NACK bits, HARQ-ARQ bits) for the correspondingcell is assumed to be 1 (non-MIMO) or m (MIMO) regardless of the numberof actually transmitted transport blocks (or codewords).

First, terms used in this specification are summarized below.

-   -   HARQ-ACK: Represents a reception response result to DL        transmission (e.g., a PDSCH or a DL SPS release PDCCH), namely,        ACK/NACK/DTX response (simply, ACK/NACK response). The        ACK/NACK/DTX response refers to ACK, NACK, DTX or NACK/DTX.        HARQ-ACK for a specific cell or the HARQ-ACK of a specific cell        represents an ACK/NACK response to a DL signal (e.g., PDSCH)        associated with (e.g., scheduled for) the cell. The PDSCH may be        replaced by a TB or codeword. HARQ-ACK is fed back for (i) an        SPS PDSCH, (ii) a PDSCH (hereinafter, normal PDSCH, non-SPS        PDSCH) scheduled by the PDCCH (DG DCI), and (iii) a DL SPS        release PDCCH (DG DCI). The SPS PDSCH does not accompany a        corresponding PDCCH (DG DCI).    -   DL SPS release PDCCH: Represents a PDCCH indicating DL SPS        release.    -   SPS PDSCH: Represents a PDSCH transmitted on DL by using a        resource semi-statically configured by SPS. The SPS PDSCH has no        corresponding DL grant PDCCH (DG DCI). In this specification,        SPS PDSCH is used interchangeably with PDSCH without (w/o) PDCCH        and SPS-based PDSCH.    -   SPS PUSCH: Represents a PUSCH transmitted on UL by using a        resource semi-statically configured by SPS. The SPS PUSCH has no        corresponding UL grant PDCCH (UG DCI). In this specification,        SPS PUSCH is used interchangeably with PUSCH w/o PDCCH.    -   ARI (ACK/NACK Resource Indicator): Used to indicate a PUCCH        resource.

In one example, the ARI may be used to indicate a resource variant value(e.g., offset) for a specific PUCCH resource (group) (configured by ahigher layer). As another example, an ARI may be used to signal aspecific PUCCH resource (group) index within a set of PUCCH resources(groups) (configured by a higher layer). The ARI may be included in theTPC (Transmit Power Control) field of the PDCCH corresponding to thePDSCH on the SCell. PUCCH power control is performed through the TPCfield in the PDCCH (i.e., the PDCCH corresponding to the PDSCH on thePCC) for scheduling the PCell. In addition, the ARI may be included inthe TPC field of the remaining PDCCHs except for the PDCCH forscheduling a specific cell (e.g., PCell) while having an initial valueof a DAI (Downlink Assignment Index). ARI is used interchangeably withHARQ-ACK resource indication value.

-   -   DAI (Downlink Assignment Index): Included in the DCI transmitted        through the PDCCH. The DAI may indicate an order value or a        counter value of the PDCCH. The DAI is used for TDD operation in        legacy LTE/LTE-A. For simplicity, the DAI of the DL grant PDCCH        is referred to as DL DAI and is referred to as the UL DAI of the        DAI in the UG PDCCH.    -   t-DAI: Represents DAI for signaling DL scheduling information in        the time domain (i.e., SF domain) within the bundling window for        each cell. This corresponds to the existing DL DAI (see DAI-c in        FIG. 15). In the present invention, the t-DAI may be modified to        signal information different from the conventional one.    -   (A/N) bundling window: The UE transmits HARQ-ACK feedback for DL        data reception in the bundling window through the UL SF. When        HARQ-ACK feedback is transmitted in SF #n, the bundling window        is defined as SF #n-k. K=4 in FDD, and k in TDD is defined by        DASI(K: {k₀, k₁, . . . k_(M−1)}) in Table 5. The bundling window        may be defined cell by cell.    -   PDCCH (DG DCI) for scheduling cell #A, cell #A scheduling PDCCH        (DG DCI): Represents PDCCH (DG DCI) for scheduling the PDSCH on        cell #A. That is, this represents PDCCH (DG DCI) corresponding        to the PDSCH on CC #A, or a DG SPS release PDCCH (DG DCI)        transmitted on CC #A.    -   Scheduling for cell #A, cell #A scheduling: Represents PDSCH or        DG SPS release PDCCH transmission on cell #A. Alternatively, it        may refer to an operation or process related to transmitting a        PDSCH or DG SPS release PDCCH on cell #A. For example, it may        mean transmitting a PDCCH for scheduling a PDSCH in        consideration of PDSCH transmission on cell #A.    -   CS S-based scheduling: Refers to transmission of (i) PDCCH        corresponding to PDSCH or (ii) DG SPS release PDCCH, in the CSS.        The CS S-based PDSCH refers to a PDSCH scheduled by the PDCCH        transmitted in the CSS.    -   CSS restriction: Indicates that the (maximum) number of        CSS-based scheduling that can be performed within the bundling        window is limited to a certain value (e.g., 1) or less.    -   SPS-based scheduling: Depending on context, may mean DG SPS        release PDCCH transmission, SPS PDSCH transmission or SPS PUSCH        transmission.    -   LCell and UCell: LCell refers to a cell operating in a licensed        band and UCell refers to a cell operating in an unlicensed band.        In the UCell, communication is performed based on carrier        sensing.

Hereinafter, a method for efficiently performing A/N feedback based onDAI signaling in the DG/UL grant DCI in a CA situation (e.g., reductionof an A/N feedback size) is proposed. Specifically, a DAI signalingscheme (through DG/UL grant DCI) and a method of constructing A/Npayload (on PUCCH/PUSCH) based on the DAI signaling scheme are proposed.In the present invention, TDD (or FDD) may include a case where thePCell or a cell performing A/N transmission operates in TDD (or FDD),and DG SF may include an S SF configured in TDD.

First, DAI (hereinafter, c-DAI) that signals DG scheduling informationat a frequency domain (i.e., CC (cell) domain) in the same DG SF (inaddition to t-DAI) may be considered.

(1) c-DAI Signaling Method Through DG/UL Grant DCI

The c-DAI (hereinafter, DL c-DAI) signaled through DL grant (DG) DCI forscheduling each DL SF may indicate: 1) a counter value (hereinafterreferred to as count-DAI) indicating the scheduling order of a cellscheduled by the DG DCI among all cells with respect to an arbitrary orspecific order (e.g., cell index order) in the corresponding DL SF, or2) the CG (hereinafter, point-DAI) to which all cells scheduled throughthe DL SF (or bundling window) belong when a plurality of cell groups(i.e., CGs) is preconfigured for all cells. Each CG may include all orsome cells, and a specific cell may be redundantly configured inmultiple CGs.

In TDD, c-DAI may be signaled for each DL SF. Characteristically, in thecase of count-DAI, considering inconsistency between the UE and the basestation on the A/N allocation on the payload due to complexity in theA/N payload configuration and the DL grant DCI missing, the c-DAI valueinitially assigned to a specific cell (within the bundling window) maybe signaled in a manner that the c-DAI value is assigned only to thecorresponding cell. More specifically, for the c-DAI value assigned to aspecific cell 1) if there is a c-DAI value pre-assigned to thecorresponding cell through the previous DL SF, it may be assigned as itis, and 2) if not, a specific one (e.g., the least/the lowest value)among c-DAI values which are not pre-assigned to all cells.

FIG. 16 illustrates a count-DAI allocation method according to thisembodiment. For example, assuming that cells 1, 2, 3 and 4 areconfigured in CA and c-DAI=1 and c-DAI=2 are assigned to cell 1 and cell3 scheduled through SF #1, respectively, c-DAI=1 and c-DAI=3 may beassigned to cell 1 and cell 2 scheduled through SF #2, respectively.With count-DAI, t-DAI may be additionally transmitted. t-DAI indicates ascheduling order value on the SF axis in each cell.

In addition, in the TDD situation, considering inconsistency between theUE and the base station on the A/N allocation on the payload due tocomplexity of A/N payload configuration, DL grant DCI missing, and thelike, point-DAI may be signaled in a manner of indicating a CG includingall pre-scheduled cells (within the bundling window).

FIG. 17 illustrates a point-DAI allocation method according to thisembodiment. For example, suppose that cells 1, 2, 3, and 4 areconfigured in CA and CGs 1, 2, and 3 are configured with cells 1/2,cells 1/2/3, and cells 1/2/3/4, respectively. When cells 1 and 2 arescheduled through SF #1, c-DAI in the DL grant DCI for scheduling SF #1may be indicated as CG 1. When cell 4 is scheduled through SF #2, c-DAImay be indicated as CG 3. When cells 1 and 3 are scheduled through SF#3, c-DAI may be indicated as CG 3. t-DAI may be further transmittedalong with point-DAI. t-DAI represents a scheduling order value on theSF axis in each cell.

The count-DAI may signal a counter value in units of CG indicating thescheduling order of a CG among all CGs when all the cells are (dividedand) configured/set in a plurality of CGs. In this case, each CG may beconstituted by only a part of cells, and each cell may be configured inonly one CG. This method may be useful in that, when the counter-DAI isconfigured by only a limited number of bits (e.g., 2 bits) (e.g., aplurality of different counter values corresponds to the samecounter-DAI bit combination by the modulo operation or the like), the UEsuccessively fails to detect a plurality of (e.g., 4) DL grant DCIS andmisinterprets the counter value in a specific DL grant DCI as anothercounter value corresponding to the same counter-DAI bit combination. Forexample, assuming that count-DAI represents the counter value in unitsof cell and counter-DAI is 2-bit counter-DAI, counter-DAI 2 bits=00, 01,10 and 11 may correspond to counter=1/5, 2/6, 3/7, and 4/8,respectively. In this case, when the UE successively fails to detectfour DL grant DCIS, the counter=6 may be misrecognized as counter=2corresponding to the same bit 01.

FIG. 18 illustrates a count-DAI allocation method when count-DAIindicates a counter value in units of CG. For example, suppose that inFDD, CGs 1, 2, and 3 are configured with cells 1/2, cells 3/4, and cell5, respectively. In this case, when cells 1, 3 and 4 are scheduled, thec-DAI values in the DG DCI corresponding to each cell are signaled as 1,2 and 2, respectively. When cells 3, 4 and 5 are scheduled, the c-DAIvalues may be signaled as 1, 1, and 2, respectively.

When the count-DAI in units of CG (hereinafter referred to as CG-unitc-DAI) is applied, A/N arrangement (on PUCCH/PUSCH) for each cell in theCG corresponding to the same c-DAI may conform to the order of cellindexes. The c-DAI allocation rule in TDD may be applied to thecount-DAI in units of CG as well. In addition, the count-DAI in units ofCG may be applied even when the (scheduling) counter value is signaledusing the CC first scheme by combining the CC (i.e., cell) domain withthe SF domain in the TDD situation. For example, in the same way as inFIG. 18, three CG configurations may be considered, and a bundlingwindow configured by three SFs may be assumed. In this case, when cells{1, 3, 4} are scheduled through SF #1, cells {1, 3, 4, 5} are scheduledthrough SF #2, and cells {1, 2} are scheduled through SF #3, the c-DAIvalues per cell in each SF may be signaled as {1, 2, 2} for SF #1, {3,4, 4, 5} for SF #2, and {6, 6} for SF #3. A CG-unit c-DAI may be appliedto a CA situation that includes a UCell, or a CA situation that includesmore than a certain number of UCells. As another method, it is possibleto increase the number of c-DAI configuration bits in the CA situationincluding (more than a certain number of) UCcells over other CAsiguation. In this case, c-DAI can be applied on a cell-by-cell basiswithout applying the CG-unit c-DAI.

Counter-DAI signaling may be configured differently for each cell group(CG) having the same maximum number of transmittable TBs, Nt. Forexample, the counter value of the scheduled cell may be signaled throughthe counter-DAI in the DG DCI corresponding to the CG with Nt=2, whilethe counter value of the scheduled TB may be signaled through thecounter-DAI in the DG DCI corresponding to the CG with Nt=1.Specifically, for a CG with Nt=2, 2-bit DAI {00, 01, 10, 11} is used toindicate the TB-level counter=2, 4, 6, 8, . . . . For a CG with Nt=1,3-bit DAI {000, 001, 010, . . . , 111} may be used to indicate thecounter=1, 2, 3, . . . , In this situation, the counter-DAI for theentire CA within one SF may count starting with the CG with Nt=2, andsignal the counter value of the CG with Nt=1 later. In this case, whenthe last DAI of the CG with Nt=1 indicates an odd counter value in aspecific SF in the TDD situation and the CG with Nt=2 is scheduled inthe next SF, how to signal/apply the corresponding counter value mayneed to be predefined. Thus, the value of counter #2 of the CG with Nt=2subsequent to the value (e.g., 3) of counter #1 of the CG with Nt=1 maybe determined to be the minimum counter value (e.g., 6) greater than orequal to the counter #1 a value (e.g., 5), which is the sum of the valueof counter #1 and Mt. Mt may be invariably set to 2, or may bedetermined to be the actually scheduled TB number (corresponding tocounter #2). The bits corresponding to a counter value between the valueof counter #la and the value of counter #2 may be processed as a NACK.The above method may be equally applied to a case where the value of theentire counter-DAI is signaled in one SF by counting the CGs from a CGwith Nt=1 and a CG with Nt=2 later.

In addition, t-DAI signaled for each cell in the TDD situation maysignal a counter value in units of SGs (hereinafter referred to asSG-unit t-DAI) indicating the scheduling position of a scheduled SF (andan SG including the same) among all SGs when all the SFs in a bundlingwindow are (divided and) configured/set in a plurality of SFs. As anexample, it may be assumed that a bundling window configured in aspecific cell consists of six SFs, and SGs 1, 2, and 3 are configuredwith SFs #1/2, SFs #3/4, and SFs #5/6, respectively. In this case, whenSFs #1, 3, 4, and 5 are scheduled, the t-DAI values in the DG DCIcorresponding to each SF may be signaled to indicate 1, 2, 2, and 3,respectively. SG-unit t-DAI can be applied only to UCell. When SFs #1,5, and 6 are scheduled, the t-DAI values may be signaled to indicate 1,2 and 2, respectively. The SG-unit t-DAI may be limitedly applied onlyto the UCell. In addition, in the case of the UCell, the number of t-DAIconfiguration bits may be increased over that in the case of the LCell(without applying the SG-unit t-DAI). Alternatively, in the case of theUCell, t-DAI signaling (field configuration) may be omitted, and the A/Nbits corresponding to the UCell may be arranged/mapped in order of SFindexes/numbers on the entire A/N payload.

Scheduling for a specific cell (e.g., PCell) (or specific (e.g., SPS orCSS based) scheduling) can be excluded from c-DAI signaling.Accordingly, the c-DAI may be signaled only through the DCI thatschedules the cells except the specific cell (or specific scheduling).Specifically, a cell-by-cell (scheduling) counter value may be allocatedto the count-DAI considering only scheduling for cells other than thespecific cell (or specific scheduling). In this case, the A/N feedbackcorresponding to the specific cell (or specific scheduling) may beconsistently included in the A/N payload on the PUCCH/PUSCH regardlessof the signaled count-DAI value (e.g., it may be disposed in/mapped tothe MSB (Most Significant Bit) or a low bit index containing the same).In addition, the point-DAI may indicate a (scheduled) CG while CGs arecomposed of only the cells other than the specific cell. Even in thiscase, the A/N feedback corresponding to the specific cell may beconsistently included in the A/N payload on the PUCCH/PUSCH regardlessof the signaled point-DAI value.

As another method, the count-DAI indicating the scheduling order of acell that is scheduled (by DG DCI) among all cells, namely, thescheduling order value, and/or the total-DAI value indicating the numberof cells scheduled among all the cells in an SF in which the DG DCItransmission is performed, namely a scheduling total value (orinformation from which the value can be inferred), may be signaledthrough the corresponding DG DCI. In the present invention, thetotal-DAI may be replaced by/considered as information indicating thecorresponding total scheduling number or last scheduling. In this case,the DAI configuration and UE operation may be performed depending onwhether the given situation corresponds to FDD or TDD as follows.

1) FDD Case

A. Alt 1: When the DAI is signaled through the DG DCI for any cell

CSS or SPS-based scheduling does not accompany DAI signaling, and onlyUSS-based scheduling of the PCell and SCell may be accompanied by DAIsignaling. Here, the count-DAI may be determined/defined as an ordervalue including (Opt 1) or excluding (Opt 2) CSS or SPS-basedscheduling. The total-DAI can be determined/defined as the total valueincluding the CSS or SPS-based scheduling. In this case, the A/N bitscorresponding to the CSS or SPS-based scheduling may be arrangedat/mapped to the MSB (i.e., A/N corresponding to counter-DAI=1) (in caseof Opt 1) or the LSB (in case of Opt 2) on the entire A/N payload. Inthe present invention, count-DAI=1 may mean the count-DAI valuecorresponding to the initial scheduling (or signaled through the DG DCIcorresponding to the initial scheduling) or the initial value of thecount-DAI. The initial value of the count-DAI may be set to a differentvalue (e.g., 0).

As another method, the count-DAI may be determined/defined as an ordervalue including CSS-based scheduling and excluding SPS-based scheduling.In addition, the total-DAI may be determined/defined as a total valueincluding CSS or SPS-based scheduling. In this case, the A/N bitcorresponding to the CSS-based scheduling may be arranged at/mapped tothe MSB (i.e., A/N corresponding to counter-DAI=1) on the entire A/Npayload, the A/N bit corresponding to the SPS-based scheduling may bearranged at/mapped to the LSB on the entire A/N payload.

In a situation where only the PDSCH (e.g., CSS or SPS-based PDSCH) thatdoes not accompany DAI (in particular, total-DAI) signaling isscheduled, PUSCH transmission may be scheduled/configured at thecorresponding A/N transmission time. In this case, the UE may 1)transmit only the A/N (e.g., 1-bit A/N) corresponding to the receptionof the PDSCH through a PUSCH piggyback, or 2) configure an A/N payloadof a predetermined (minimum) size (e.g. the number of the A/N bits(e.g., 4 or 8) corresponding to up to the maximum counter value (e.g.,4)) and transmit the A/N payload through a PUSCH piggyback, or 3)configure an A/N payload of the maximum size (corresponding to, forexample, the number of A/N bits corresponding to up to the last countervalue on the assumption that all cells/SFs (i.e., pairs of a cell and anSF (cell-SF pairs)) are scheduled) and transmit the A/N payload througha PUSCH piggyback. In cases 2) and 3), the A/N (e.g., 1-bit A/N)corresponding to PDSCH reception may be arranged at/mapped to the MSB orLSB on the entire A/N payload. The aforementioned operations may belimitedly performed (while there is no total-DAI received through the DGDCI) (i) when no UG DCI transmission corresponding to the PUSCH isaccompanied, or (ii) when the UL DAI (corresponding to the total-DAI) isnot signaled through the UG DCI corresponding to the PUSCH.

When there is only total-DAI received through the DG DCI for A/Npiggyback transmission on the PUSCH or there is only UL DAI(corresponding to the total-DAI) received through the UG DCI, the UE mayconfigure an A/N payload based on one DAI (total-DAI or UL DAI) value.For A/N piggyback transmission through the PUSCH, there may be the totalDAI received through the DG DCI and the UL DAI received through the UGDCI and the values thereof may be different from each other. In thiscase, the UE may 1) transmit an A/N on the PUSCH by configuring an A/Npayload based on the UL DAI value, 2) transmit an A/N on the PUSCH byconfiguring an A/N payload based on the maximum value between the UL DAIand the total-DAI, 3) transmit an A/N on the PUCCH (omitting/discardingPUSCH transmission) by configuring an A/N payload based on the total-DAIvalue, or 4) transmit an A/N on the PUCCH (omitting/discarding PUSCHtransmission) by configuring an A/N payload based on the maximum valuebetween the UL DAI and the total-DAI.

As another method, piggyback transmission for the A/N may be limited tobe performed only on the PUSCH having the same UL DAI value as thetotal-DAI. A PUSCH having a UL DAI value different from the total-DAImay be transmitted without A/N piggyback, or may be omitted/discarded.If there is no PUSCH having the same UL DAI value as the total-DAI, theUE may transmit an A/N on the PUCCH by configuring an A/N payload basedon the total-DAI value with all transmissions omitted/discarded as incase 3).

Even in the case where only the PDSCH (e.g., CSS-based PDSCHcorresponding to count-DAI=1) (or SPS-based PDSCH) that does notaccompany total-DAI signaling and ARI signaling together is scheduled,and the UCI including a corresponding A/N is transmitted through PUCCHformat 3 (PF3) or PUCCH format 4 (PF4) configured (semi-staticallythrough higher layer signaling) for use in periodic CSI transmission,configuration of an A/N payload on the PUCCH and A/N bitarrangement/mapping may be performed in a manner similar to the methoddescribed above.

As another method, when UCI including an A/N is transmitted on a PUSCHor a PUCCH (e.g., a PUCCH configured for periodic CSI transmission), theA/N bits (e.g., 1 bit) corresponding to PDSCH scheduling (e.g., CSS orSPS-based PDSCH scheduling) that does not accompany total-DAI and/or ARIsignaling may be transmitted within the A/N payload on the PUSCH or theentire UCI payload on the PUCCH in a manner that the A/N bits are alwaysallocated to/configured at a specific position (e.g., LBS or MSB) on theA/N payload (regardless of actual scheduling).

B. Alt 2: When the DAI is Signaled Only Through the DG DCI for the SCell

Scheduling for the PCell may not accompany DAI signaling, but the DAIsignaling may be accompanied only in scheduling for the SCell. In thiscase, the count-DAI may be determined/defined as an order value (Opt 1)including or (Opt 2) excluding PCell scheduling. The total-DAI may bedetermined/defined as the total sum including PCell scheduling. The A/Nbits corresponding to the PCell scheduling may be arranged at/mapped tothe MSB (i.e., considered as an A/N corresponding to counter-DAI=1) (incase of Opt 1) or LSB (in case of Opt 2) on the entire A/N payload.

2. TDD Case

A. Alt 1-1: When the DAI is Signaled Through the DG DCI for any Cell

SPS-based scheduling may not accompany DAI signaling, but CSS-basedscheduling may accompany count-DAI signaling only (without total-DAIsignaling). USS-based scheduling of the PCell and the SCell mayaccompany count-DAI signaling and total-DAI signaling. In this case, thecount-DAI may be determined/defined as an order value excludingSPS-based scheduling, and the total-DAI may be determined/defined as thetotal value including CSS or SPS-based scheduling. Here, the A/N bitscorresponding to SPS-based scheduling may be arranged at/mapped to theLSB on the entire A/N payload. In this case, a TPC command may betransmitted through the TPC field of the PCell scheduling DG DCI withcount-DAI=1, and the ARI may be transmitted through the TPC field of theremaining DG DCI (i.e., DG DCI without count-DAI=1 or SCell schedulingDG DCI). Therefore, when only PCell scheduling and/or SPS-basedscheduling with count-DAI=1 is received, the UE may transmit only theA/N corresponding to the scheduling using PUCCH format 1a/1b (withchannel selection).

In the case of SPS-based scheduling, PUCCH format 1a/1b (i.e., PF1)resource candidate(s) for A/N transmission for the SPS PDSCH arepreconfigured through higher layer (e.g., RRC) signaling and one of theresource candidates(s) is allocated as an A/N transmission PF1 resourcecorresponding to the SPS PDSCH through the TPC field in the PDCCHindicating DL SPS activation. According to operation of the presentinvention, ARI indicating one of a plurality of PF3 or PF4 resources maybe signaled through a TPC field in a DG PDCCH that has a count-DAI valueother than count-DAI=1 and schedules the PCell. If the PDCCH is a PDCCHindicating DL SPS activation, PF1 resources for SPS may also need to beindicated through the TPC field. In this case, the PF3/PF4 resource andthe PF1 resources for the SPS may need to be indicated simultaneously byone TPC field, which may lower the freedom of resource selection foreach of the PF3/PF4 resources and the PF1 resources for SPS.

In view of this, only the PF1 resources for SPS may be indicated throughthe TPC field in the PDCCH indicating DL SPS activation (withoutindicating other resources such as PF3/PF4 resources). That is, the TPCfield in the PDCCH indicating DL SPS activation may be used only toindicate the PF1 resources for SPS regardless of the count-DAI value.Accordingly, even when only the PDCCH indicating DL SPS activationand/or PCell scheduling DG DCI having count-DAI=1 are received, only theA/N corresponding to the PDCCH/scheduling may be transmitted using PUCCHformat 1a/1b (with channel selection). At this time, the A/N resourcesfor the PDSCH corresponding to the DL SPS activating PDCCH 1) may beassigned PF1 resources implicitly linked to the corresponding PDCCHtransmission resources (Equation 1), or 2) may be assigned PF1 resourcesfor SPS indicated through the TPC field in the corresponding PDCCH. Theproposed method may be equally applied to the existing t-DAIsignaling-based TDD situation (by replacing count-DAI with t-DAI).

When only a PDSCH (e.g., CSS and/or SPS-based PDSCH) which does notaccompany DAI (in particular, total-DAI) signaling is scheduled, PUSCHtransmission may be scheduled/configured at the time of correspondingA/N transmission. In this case, the UE 1) may transmit only the A/N(e.g., a 1-bit A/N if one of the CSS and the SPS is scheduled, a 2-bitA/N if both the CSS and the SPS are scheduled, on the assumption of aCSS restriction) corresponding to reception of the PDSCH on the PUSCH,2) configure an A/N payload of a predetermined (minimum) size (e.g. thenumber of A/N bits (e.g., 4 or 8) corresponding to up to the maximumcounter value (e.g., 4)) and transmit the same on the PUSCH, or 3)configure an A/N payload of the maximum size (corresponding to, forexample, the number of A/N bits corresponding to up to the last countervalue on the assumption that all cells/SFs are scheduled) and transmitthe same on the PUSCH. In cases 2) and 3), the A/N (e.g., 1-bit A/N or2-bit A/N) corresponding to the PDSCH reception may be arrangedat/mapped to the MSB or LSB on the entire A/N payload. Theaforementioned operations may be limitedly performed (while there is nototal-DAI received through the DG DCI) when no UG DCI transmissioncorresponding to the PUSCH is accompanied, or when the UL DAI(corresponding to the total-DAI) is not signaled through the UG DCIcorresponding to the PUSCH.

There may be only total-DAI received through the DG DCI for A/Npiggyback transmission on the PUSCH or there is only UL DAI(corresponding to the total-DAI) received through the UG DCI. In thiscase, the UE may configure an A/N payload based on one DAI (total-DAI orUL DAI) value. For A/N piggyback transmission through the PUSCH, theremay be the total DAI received through the DG DCI and the UL DAI receivedthrough the UG DCI and the values thereof may be different from eachother. In this case, the UE may 1) transmit an A/N on the PUSCH byconfiguring an A/N payload based on the UL DAI value, 2) transmit an A/Non the PUSCH by configuring an A/N payload based on the maximum valuebetween the UL DAI and the total-DAI, 3) transmit an A/N on the PUCCH(omitting/discarding PUSCH transmission) by configuring an A/N payloadbased on the total-DAI value, or 4) transmit an A/N on the PUCCH(omitting/discarding PUSCH transmission) by configuring an A/N payloadbased on the maximum value between the UL DAI and the total-DAI. Asanother method, piggyback transmission for the A/N may be limited to beperformed only on the PUSCH having the same UL DAI value as thetotal-DAI. In this case, a PUSCH having a UL DAI value different fromthe total-DAI may be transmitted without A/N piggyback, or may beomitted/discarded. If there is no PUSCH having the same UL DAI value asthe total-DAI, the UE may transmit an A/N on the PUCCH by configuring anA/N payload based on the total-DAI value with all transmissionsomitted/discarded as in case 3).

CS S-based scheduling may include count-DAI signaling through thecorresponding DG DCI. In this situation, when only the CSS-based PDSCHis scheduled, the UE may Opt 1) configure only an A/N payloadcorresponding to the counter-DAI value and transmit the same on thePUSCH, or Opt 2) configure an A/N payload of a predetermined (minimum)size and transmit the same on the PUSCH, wherein an A/N for reception ofthe CSS-based PDSCH may be arranged at/mapped to the bits correspondingto the counter-DAI value on the payload. If there is additionalSPS-based scheduling in this situation, the UE may 1) add 1 bit to theend (or start) of the payload configured based on Opt 1 and arrange/mapthe A/N corresponding to reception of the SPS-based PDSCH at/to the 1bit, namely the LSB (or MSB) on the entire payload, or 2) arrange/mapthe A/N corresponding to reception of the SPS-based PDSCH at/to the LSB(or MSB) on the payload configured based on Opt 2, wherein, if the A/Ncorresponding to reception of the SPS-based PDSCH has already beenarranged at/mapped to the LSB (or MSB), 1 bit may be added to the end(or start) of the payload and the A/N corresponding to reception of theSPS-based PDSCH may be arranged at/mapped to the 1 bit.

When only a PDSCH (e.g., CSS-based PDSCH corresponding to count-DAI>1)(and/or an SPS-based PDSCH) that accompanies ARI signaling indicating aPF3 resource or a PF4 resource without involving total-DAI signaling isscheduled, the UCI including the corresponding A/N may be transmittedthrough PF3 or PF4 indicated by the ARI. In this case, A/N payloadconfiguration and A/N bit arrangement/mapping on the PUCCH may beperformed in a manner similar to the above method (e.g., Opt 1 to 2).When only a PDSCH (e.g., CSS-based PDSCH corresponding to count-DAI=1)(and/or an SPS-based PDSCH) that does not accompany either total-DAIsignaling or ARI signaling (e.g., CSS-based PDSCH corresponding tocount-DAI=1) is scheduled, the UCI including the corresponding A/N maybe transmitted through PF3 or PF4 configured for periodic CSItransmission (semi-statically through higher layer signaling). In thiscase, the A/N payload configuration and A/N bit arrangement/mapping onthe PUCCH may be performed in a similar manner (e.g., Opt 1 to 2).

As another method, when the UCI including an A/N is transmitted on aPUSCH or a PUCCH (e.g., a PUCCH indicated by the ARI or a PUCCHconfigured for periodic CSI transmission), the A/N bits (e.g., 2 bits or1 bit) corresponding to PDSCH scheduling (e.g., CSS or SPS-based PDSCHscheduling) that does not accompany total-DAI and/or ARI signaling maybe transmitted within the A/N payload on the PUSCH or the entire UCIpayload on the PUCCH in a manner that the A/N bits are always allocatedto/configured at a specific position (e.g., LBS or MSB) on the A/Npayload (regardless of actual scheduling). In addition, if the CSSrestriction is not separately configured, the number of A/N bitsconsistently allocated to/configured at a specific position of the A/Npayload (regardless of whether or not scheduling is actually performed)may be determined/set to be the M bits as M, the number of DL (or S) SFsin the bundling window.

B. Alt 1-2: When the DAI is Signaled Through the DG DCI for any Cell

SPS and CSS-based scheduling may accompany none of count-DAI signalingand total-DAI signaling, but count-DAI and total-DAI signaling may beaccompanied only in US S-based scheduling of the PCell and the SCell.The t-DAI field in the CSS-based DG DCI may be set to a fixed value(e.g., 0). In USS-based scheduling, the count-DAI is determined/definedas an order value excluding SPS or CS S-based scheduling, and thetotal-DAI may be determined/defined as a total value including CSS orSPS-based scheduling. Here, the A/N bits corresponding to theSPS/CSS-based scheduling may be arranged at/mapped to the LSB in theentire A/N payload. In addition, the (maximum) number of CSS-basedscheduling operations that may be performed within the bundling windowmay be limited to a certain value (e.g., 1) or less (CSS restriction).In this case, the TPC command may be transmitted through the TPC fieldof the PCell scheduling DG DCI with count-DAI=1 and the DG DCItransmitted through the CSS. The ARI may be transmitted through the TPCfield of the remaining DG DCI (i.e., DG DCI not count-DAI=1 or SCellscheduling DG DCI). Therefore, when only PCell scheduling and/orSPS/CSS-based scheduling with count-DAI=1 is received, the UE maytransmit only the A/N corresponding to the scheduling using PUCCH format1a/1b (with channel selection).

C. Alt 2: DAI is Signaled Only Through the DG DCI for the SCell

PCell scheduling may accompany existing t-DAI signaling withoutsignaling for the count-DAI/total-DAI, and the count-DAI and total-DAIsignaling may be accompanied only in SCell scheduling. In this case, thecount-DAI may be determined/defined as an order value excluding PCellscheduling, and the total-DAI may be determined/defined as the totalvalue excluding PCell scheduling. Separately, the (maximum) number ofA/N bits corresponding to the entire PCell may be consistently reservedin the A/N payload. The A/N bits corresponding to PCell scheduling maybe arranged at/mapped to the MSB or the LSB in the entire A/N payload.As another method, the total-DAI may be determined/defined as the totalvalue including PCell scheduling (and the count-DAI may bedetermined/defined as an order value excluding PCell scheduling). Inthis case, for the A/N payload configuration, Opt 1) an A/Ncorresponding to the t-DAI may be mapped to the MSB side (in order oft-DAI values) and an A/N corresponding to the count-DAI may be mapped tothe LSB side (in reverse order of the count-DAI values), or conversely,Opt 2) the A/N corresponding to the count-DAI may be mapped to the MSBside (in order of the count-DAI values), and the A/N corresponding tothe t-DAI may be mapped to the LSB side (in reverse order of the t-DAIvalues). For example, in the case of Opt 1, A/N mapping may be performedon the A/N payload in the form of {t-DAI=1, t-DAI=2, t-DAI=3, . . . ,count-DAI=3, count-DAI=2, count-DAI=1}. In the case of Opt 2, A/Nmapping may be performed on the A/N payload in the form of {count-DAI=1,count-DAI=2, count-DAI=3, . . . , t-DAI=3, t-DAI=2, t-DAI=1}.

In this case, the TPC command may be transmitted through the TPC fieldof the PCell scheduling DG DCI with t-DAI=1, and the ARI may betransmitted through the TPC field of the remaining DG DCI (i.e., DG DCIwithout t-DAI=1 or SCell scheduling DG DCI). Accordingly, upon receivingonly PCell scheduling and/or SPS-based scheduling with t-DAI=1, the UEmay transmit only the A/N corresponding to the scheduling using PUCCHformat 1a/1b (with channel selection). Here, PUCCH format (or resource)A indicated by the ARI signaled through the (PCell scheduling) DG DCIcorresponding to t-DAI>1 may be set to be the same as or different fromPUCCH format (or resource) B indicated by the ARI signaled through the(SCell scheduling) DG DCI corresponding to the count-DAI. In the casewhere two ARIs are set to indicate different PUCCH formats (orresources), PUCCH format (or resource) B may be selected to perform A/Ntransmission when DG DCI corresponding to the count-DAI is received, andPUCCH format (or resource) A may be selected to perform A/N transmissionwhen only DG DCI corresponding to the t-DAI is received.

As another method, in the case of DG DCI transmitted through the CSS,the total-DAI may be signaled through the TPC field in the DCI. In thiscase, the TPC command for PUCCH power control may not be signaledthrough the CSS-based DG DCI. Alternatively, in FDD, the count-DAI maybe signaled through the TPC field in the CSS-based DG DCI. In TDD, thetotal-DAI may be signaled through the TPC field in the CSS-based DG DCI(in TDD, this may be the case of all or specific CS S-based DG DCIS(corresponding to, for example, count-DAI=1). In this case, the TPCcommand for the PUCCH may not be signaled through the CSS-based DG DCI.

As another method, in FDD and TDD, when the count-DAI and the total-DAIare defined/configured to signal the scheduling order or the totalnumber of a PDSCH accompanying a corresponding DG DCI transmission or aPDCCH transmitted for a specific purpose (e.g., indicating a DL SPSrelease), the UE may configure the entire A/N payload (e.g., N bits)with A/N bits (e.g., N bits) corresponding to the total-DAI. If thereare multiple DG DCIS, the DG DCIS in the same SF have the same value oftotal-DAI. If SPS-based PDSCH transmission is to be performed, the UEmay configure the entire A/N payload (e.g., N+1 bits) by adding A/N bit(e.g., 1 bit) for the SPS-based PDSCH to A/N bits (e.g., N bits)corresponding to the total-DAI. The entire A/N payload may betransmitted on the PUCCH or PUSCH. The A/N bits corresponding to theSPS-based PDSCH may be arranged at/mapped to the MSB or the LSB on theentire A/N payload.

Meanwhile, in the TDD situation, the counter-DAI may be replaced by/usedas signaling indicating a (scheduling) counter value in the CC firstscheme in the CC and SF domains (i.e., the CC/SF domain or the cell/SFdomain) by combining the CC (i.e., cell) domain with the SF domain. Forexample, the counter-DAI may indicate the scheduling order of a cell,that is scheduled (by the DG DCI), among all cells, i.e., the schedulingorder value in units of cell/SF (pair of cell and SF). In the CC firstscheme, the scheduling order in units of cell/SF is calculated in orderof increasing SF index after increasing the CC (i.e., cell) index in thebundling window. In addition, the total-DAI may be replacedwith/considered as signaling indicating the scheduling total value basedon the counter-DAI signaling. Specifically, the total-DAI may bedefined/signaled to indicate the cumulative scheduling total value(e.g., the sum of the cells scheduled by the DG DCI) along the DL SF.For example, when it is assumed that three, two, and four cells arescheduled through DL SFs #1, #2 and #3, respectively, in a situationwhere the A/Ns for DL SFs #1, 2 and 3 are transmitted through one UL SF,the total-DAI may be defined/signaled to indicate total-DAI=3 for DL SF#1, total-DAI=5 for DL SF #2, and total-DAI=9 for DL SF #3.

FIG. 19 illustrates a count-/total-DAI allocation method according tothis embodiment. It is assumed that cells 1, 2, 3, and 4 are subjectedto CA for the UE, and that the bundling window is composed of SF #1 toSF #3. Referring to FIG. 19, cell/SF resources of (Cell 1, SF #1), (Cell2, SF #1), (Cell 4, SF #2), (Cell 1, SF #3), and (Cell 3, SF #3) arescheduled, and the other cell/SF resources are not scheduled. Here,scheduling means that DL transmission for which HARQ-ACK feedback isrequired is performed in the corresponding cell/SF resource, and DLtransmission for which HARQ-ACK feedback is required includes a PDSCHand an SPS release PDCCH. For example, there may be PDSCH transmissionin (Cell 2, SF #1). In this case, the PDCCH for scheduling the PDSCH maybe transmitted in (Cell 2, SF #1) (self-scheduling) or transmitted in(Cell X, SF #1) (cross-carrier scheduling) according to the schedulingscheme. Cell X denotes a scheduling cell of cell 1. The SPS PDSCH doesnot accompany count-DAI/total-DAI, and the figure illustrates only acase where the PDSCH scheduled by the PDCCH (DG DCI) (and SPS releasePDCCH) is scheduled. In this embodiment, the count-DAI indicates the(scheduling) counter value in the cell first scheme and thereforeindicates 1 to 5 in order of (Cell 1, SF #1)=>(Cell 2, SF #1)=>(Cell 4,SF #2)=>(Cell 1, SF #3)=>(Cell 3, SF #3). In addition, the total-DAIindicates the accumulative scheduling total value along the DL SF.Therefore, the total-DAI indicates total-DAI=2 for SF #1, total-DAI=3for SF #2, and total-DAI=5 for DL SF #3, respectively. In the same SF,the total-DAIS have the same value. The count-/total-DAI is used for theHARQ-ACK transmission procedures (HARQ-ACK payload configuration,HARQ-ACK bit positioning, DTX detection, etc.).

If a method of signaling the total-DAI value other than theabove-described method is considered, a problem may arise.

For example, if the total-DAI is defined to individually indicate onlythe scheduling total value in each DL SF (total-DAI=2 for SF #1 andtotal-DAI=2 for SF #=1 and total-DAI=2 for DL SF #3 in the exampleabove), there may be a problem in matching the A/N payload between thebase station and the UE when all the DG DCIS in a specific DL SF aremissing.

In another example, if the total-DAI is defined to indicate the totalscheduling value in all DL SFs (total-DAI=5 for SF #1, total-DAI=5, andtotal-DAI=5 for DL SF #3), the burden on the BS scheduler, which mustpredict scheduling at a future time, may be increased.

In the above example, the total-DAI may be configured to indicate onlysome representative values among all possible scheduling sum (i.e.,total) values. In this case, in a situation where the total-DAI consistsof only a limited number of bits (e.g., 2 bits) (e.g., a plurality ofdifferent total values corresponds to the same total-DAI bit combinationby the modulo operation or the like), if the UE successively fails todetect a plurality of DG DCIS (e.g., 4 DG DCIS) and thus misrecognizesthe total value in a specific DG DCI as another total valuecorresponding to the same total-DAI bit combination (e.g., whentotal-DAI 2-bits=00, 01, 10 and 11 correspond to total=1/5, 2/6, 3/7 and0/4/8, respectively, total=7 is misrecongized as total=3 correspondingto the same bit 10). For example, when total-DAI 2-bits=00, 01, 10, and11 are set to correspond to total=2/10, 4/12, 6/14, and 0/8/16, 8,respectively (i.e., multiple of 2 through application of modulo-8), thebase station may indicate a total-DAI corresponding to the minimum totalvalue among the total values that are greater than or equal to the totalvalue scheduled by the base station, and the UE may assume thisoperation. In another method, when the total number of cells is assumedto be N, total-DAI 2-bits=00, 01, 10, and 11 may be set to correspond tototal=N1, N2, N3, N (N1>N2>N3>N) (without separate modulo operation)(hereinafter, quantized total-DAI). The quantized total-DAI may beapplied to CA that includes a UCell or CA that includes more than acertain number of UCells. In another method, in the situation of CAincluding (more than a certain number of) UCells, the number oftotal-DAI configuration bits may be increased (without applyingquantized total-DAI) over the other CA situation.

The c-DAI (i.e., UL c-DAI) signaled through the UG DCI may indicate 1)the maximum value of the DL count-DAI or the (maximum) total-DAI valueas in conventional cases if the DL c-DAI is count-DAI (alternatively,the UE considers the received UL c-DAI value as the maximum value of theDL count-DAI or the total-DAI (maximum) value) (hereinafter, ULcount-DAI), or 2) the finally scheduled CG index or (last) signaled DLpoint-DAI value if the DL c-DAI is point-DAI (or if there is nosignaling for the DL c-DAI) (alternatively, the UE regards the receivedUL c-DAI value as a scheduled CG index or a corresponding DL point-DAIvalue) (hereinafter, UL point-DAI).

In addition, the UL c-DAI may be configured to indicate only a specificpart of the total DL c-DAI values (in the case of the count-DAI), and atleast the maximum value of the DL c-DAI may be included in some specificDL c-DAI values. For example, assuming that the DL c-DAI can have Nvalues from 1 to N (>4) and the UL c-DAI is set to 4 values, one of thefour values DL c-DAI=1, 2, 4, N may be signaled through the UL c-DAI.

Meanwhile, in the present invention, for the total-DAI signal signaledthrough the DG DCI and/or the UL count-DAI signaled through the UG DCI,the base station may signal a specific value (hereinafter, Ntot) (notseparately defined) through the DG DCI and/or the UG DCI. In this case,the UE may recognize the value of Ntot as the total of the schedulingnumbers (from the base station) in all the cells (or SFs) constitutingCA or the last scheduling counter value, and configure/transmit thecorresponding A/N payload. For example, when 2-bit Ntot is considered,state 00 may indicate k×(4n+1), state 01 may indicate k×(4n+2), state 10may indicate k×(4n+3), and state 11 may indicate k×(4n+4). Here, n=0, 1,. . . , and k>1. Accordingly, the UE may consider the minimum totalvalue greater than or equal to the (maximum) counter value last receivedby the UE among the values (hereinafter, total values) indicated by Ntotas the total of scheduling numbers (from the base station) in all thecells (SFs) constituting the CA, and configure/transmit thecorresponding A/N payload. The value of k may be set by the basestation.

In FDD, the UL count-DAI may not be signaled over UG DCI transmittedthrough the CSS. The UL counter-DAI may be signaled only over UG DCItransmitted through the USS. In TDD, the UL counter-DAI may be signaledover both UG DCIS transmitted through the CSS and the USS. In this case,the UL counter-DAI may be signaled through the existing t-DAI field.

In the case of a PUSCH that is not scheduled from UG DCI including ULc-DAI (e.g., a PUSCH scheduled based on the SPS (or CSS) or a PUSCHretransmitted without corresponding DCI), the UE may configure andtransmit an A/N payload, assuming/considering the (maximum) total-DAIvalue or the (last) point-DAI value received from the DG DCI as ULc-DAI. When the counter-DAI is independently applied to each CG, a ULc-DAI value for a plurality of CGs may be signaled through one UG DCI.The UL c-DAI for each CG may signal only whether there is DL schedulingfor each CG (or whether there is A/N feedback corresponding to each CG)(in order to reduce DCI overhead). Here, the CGs may be configuredaccording to a specific criterion. For example, cell(s) having the samemaximum number of transmittable TBs or cell(s) having the same carriertype (e.g., LCell or UCell) may be bundled into a CG. In addition, whenthe total-DAI or point-DAI is signaled through the DG DCI, separate ULc-DAI signaling (and field configuration therefor) may be omitted fromthe UG DCI. In this case, the UE may configure/transmit a correspondingA/N payload, assuming/considering the (maximum) total-DAI value or the(last) point-DAI value received from the DG DCI for all PUSCHs as the ULc-DAI.

With the proposed method, the A/N payload may be effectively reduced theeven on an existing PUSCH that does not allow reduction of the A/Npayload size (e.g., a PUSCH that is not scheduled from UG DCI includingUL c-DAI (e.g., a PUSCH scheduled based on the SPS (or CSS), a PUSCHretransmitted without corresponding DCI, or any PUSCH in FDD)). Inaddition, through this operation, UL-SCH and/or UCI transmissionperformance on the PUSCH may be improved.

Meanwhile, as the DL transmission mode (TM) is independently configuredfor each cell, the maximum number of transmittable TBs, Nt, may be setdifferently for each cell (e.g., coexistence of a cell with Nt=2 and acell with Nt=1). In this situation, when the count-DAI signals thescheduling order (counter) value in units of cell/SF, if the UE fails todetect the DG DCI having the count-DAI, the UE cannot correctlyrecognize a cell corresponding to the count-DAI and the TM (i.e., thevalue of Nt) set for the cell. Thereby, inconsistency may occur betweenthe UE and the base station in determining the number of A/N bitscorresponding to the counter-DAI. In consideration of such a problem,when Nt is set differently for each cell (e.g., a cell with Nt=2exists), the count-DAI may signal the scheduling order (counter) valuein units of cell/SF, and the number of A/N bits corresponding to eachcell/SF may be allocated so as to be equal to the maximum value of Nt,namely, i.e., max−Nt (e.g., max−Nt=2), irrespective of the TM of thecell.

In the above situation, the total number of A/N bits (tot-Ns)×(max−Nt)corresponding to tot-Ns may exceed the maximum number of A/N bits, i.e.,max−Na, given when the number of A/N bits is allocated according to theoriginal cell-specific TM, i.e., Nt. Here, tot-Ns denotes the totalnumber of scheduled cells/SFs inferred from the scheduling counter valuecorresponding to the last counter-DAI or the total-DAI (and/or the ULcount-DAI signaled through the UG DCI). In addition, max−Na denotes thetotal number of A/N bits allocated to all cells when A/N bitscorresponding to the total number of SFs in the bundling window of thecorresponding cell are allocated to each cell based on Nt set for thecorresponding cell. If (tot−Ns)×(max−Nt)>max−Na or(tot−Ns)×(max−Nt)>max−Na, the UE may configure only A/N bitscorresponding to max−Na in an A/N payload such that the A/N bits aremapped to the A/N payload in order of cell/SF indexes rather than inorder of counter-DAIS. On the other hand, if (tot−Ns)×(max−Nt)≤max−Na or(tot−Ns)×(max−Nt)<max−Na, the UE may configure only A/N bitscorresponding to (tot−Ns)×(max−Nt) in an A/N payload such that the A/Nbits are mapped to the A/N payload in order of counter-DAIs.

(2) A/N Payload Configuration Based on DL/UL c-DAI

A method of configuring an A/N payload on a PUCCH/PUSCH when the DL/ULc-DAI signaling scheme is applied (particularly, in TDD) is discussed.In TDD, 1) the t-DAI and the c-DAI may be signaled simultaneously(hereinafter, referred to as a case with t-DAI), or 2) only the c-DAImay be signaled without signaling of the t-DAI (hereinafter, referred toas a case w/o t-DAI). In the latter case, the c-DAI (rather than thet-DAI) may be signaled through the DAI field in an existing DCI format.Hereinafter, a method of configuring an A/N payload on a PUCCH/PUSCHaccording to presence/absence of t-DAI signaling, the DL c-DAI signalingscheme, and presence/absence of the UL c-DAI will be discussed. A/Ntransmission on the PUCCH may be included in a case without UL c-DAI,which will be described below.

(a) When Both DL Count-DAI and UL Count-DAI are Present

1) A Case with t-DAI (i.e., when Both DL t-DAI/UL t-DAI are Present)

To configure an A/N payload, A/Ns corresponding to DL c-DAI values from1 to UL c-DAI may be arranged along the cell-axis in order of the DLc-DAI values (assuming that the initial values of the DL c-DAI and theDL t-DAI are 1), and A/Ns corresponding to DL t-DAI values from 1 to ULt-DAI (for each cell) may be arranged along the SF-axis in order of theDL t-DAI values (for all DL c-DAI values regardless of the value of Mfor each cell). This is because, when the UE misses a specific DL c-DAI(DG DCI including the DL c-DAI), inconsistency between the UE and thebase station may occur in terms of the value of M set for a cellcorresponding to the DL c-DAI. A DL c-DAI and a DL t-DAI that are notdetected/received may be processed as NACK or DTX.

2) A Case w/o t-DAI (i.e., when there is No DL/UL t-DAI)

To configure an A/N payload, A/Ns corresponding to DL c-DAI values from1 to UL c-DAI may be arranged along the cell-axis in order of the DLc-DAI values, and A/Ns corresponding to DL SFs from the first DL SF tothe max-M-th DL SF (for each cell) may be arranged in order of the DLSFs (for all DL c-DAI values regardless of the value of M for each cell)along the SF-axis. max-M may be the maximum value among the M values setfor all the cells. This is because, when the UE misses a specific DLc-DAI (DG DCI including the DL c-DAI), inconsistency between the UE andthe base station may occur in terms of the value of M corresponding tothe DL c-DAI. A DL c-DAI and a DL SF that are not detected/received maybe processed as NACK or DTX.

(B) When DL Count-DAI is Present and UL Count-DAI is not Present

1) A Case with t-DAI (i.e., when there is DL t-DAI and No UL t-DAI)

To configure an A/N payload, A/Ns corresponding to the values from 1 tothe greatest value among the received DL c-DAIs, a specific (preset) DLc-DAI having a value greater than or equal to the greatest value, or themaximum value that the DL c-DAI may have may be arranged in order of theDL c-DAI values along the cell-axis, and A/Ns corresponding to DL t-DAIvalues from 1 to max-M (for each cell) may be arranged in order of theDL t-DAI values (for all DL c-DAI values regardless of the value of Mfor each cell) along the SF-axis. A DL c-DAI and a DL t-DAI that are notdetected/received may be processed as NACK or DTX.

2) A Case w/o t-DAI (i.e., when there is No DL/UL t-DAI)

To Configure an A/N Payload, A/Ns Corresponding to the Values from 1 tothe greatest value among the received DL c-DAIS, a specific (preset) DLc-DAI having a value greater than or equal to the greatest value, or themaximum value that the DL c-DAI may have may be arranged in order of theDL c-DAI values along the cell-axis, and A/Ns corresponding to DL SFsfrom the first DL SF to the max-M-th DL SF (for each cell) may bearranged in order of the DL SFs (for all DL c-DAI values regardless ofthe value of M for each cell) along the SF-axis. A DL c-DAI and a DL SFthat are not detected/received may be processed as NACK or DTX.

(c) When there is UL Point-DAI Regardless of Presence/Absence of DLPoint-DAI

1) A Case with t-DAI (i.e., when Both DL/UL t-DAIS are Present)

To configure an A/N payload, A/Ns corresponding to the CGs indicated bythe UL c-DAI may be arranged in order of cell indexes along thecell-axis, and A/Ns corresponding to the DL t-DAI values from 1 to min(UL t-DAI, M) (for each cell) may be arranged in order of the DL t-DAIvalues along the SF-axis. A cell and a DL t-DAI that are notdetected/received may be processed as NACK or DTX.

2) A Case w/o t-DAI (i.e., when there is No DL/UL t-DAI)

To configure an A/N payload, A/Ns corresponding to the CGs indicated bythe UL c-DAI may be arranged in order of cell indexes along thecell-axis, and A/Ns corresponding to the DL SFs from the first DL SF tothe M-th DL SF (for each cell) may be arranged in order of the DL SFsalong the SF-axis. A cell and a DL SF that are not detected/received maybe processed as NACK or DTX.

(d) When there is a DL Point-DAI and No UL Point-DAI

1) A Case with t-DAI (i.e., when there is DL t-DAI and No UL t-DAI)

To configure an A/N payload, A/Ns corresponding to a CG having thelargest number of cells among the CGs indicated by the DL c-DAI orcorresponding to all the cells may be arranged in order of cell indexesalong the cell-axis, and A/Ns corresponding to DL t-DAI values from 1 toM (for each cell) may be arranged in order of the DL t-DAI values alongthe SF-axis. A cell and a DL t-DAI that are not detected/received may beprocessed as NACK or DTX.

2) A Case w/o t-DAI (i.e., when there is No DL/UL t-DAI)

To configure an A/N payload, A/Ns corresponding to a CG having thelargest number of cells among the CGs indicated by the DL c-DAI orcorresponding to all the cells may be arranged in order of cell indexesalong the cell-axis, and A/Ns corresponding to DL SFs from the first DLSF to the M-th DL SF (for each cell) may be arranged in order of the DLSFs along the SF-axis. A cell and a DL SF that are not detected/receivedmay be processed as NACK or DTX.

Meanwhile, an ARO (ACK/NACK Resource Offset) for indicating an offsetfor implicit PUCCH (format 1a/1a) resource indexes (see Equation 1)linked to EPDCCH transmission resources may be added to the DG DCIcorresponding to the cell for which EPDCCH-based scheduling isconfigured. However, in the method of transmitting an A/N based onexplicit PUCCH resources such as PF3/PF4 configured through RRC, the AROin the DG DCI corresponding to the remaining SCells except the PCell isactually used for no purpose. Accordingly, a counter-DAI, a point-DAI ora total-DAI (or information indicating the total scheduling number orthe last scheduling corresponding thereto) may be signaled through theARO field in the DG DCI corresponding to the SCell for whichEPDCCH-based scheduling is configured.

In this embodiment, the counter-DAI and/or total-DAI may be used as aTB-level counter-DAI and/or total-DAI indicating the scheduling positionof a scheduled TB and the total number of scheduled TBs, rather than asa cell-level DAI indicating the scheduling positions of scheduled cellsor the total number of scheduled cells. Even when the counter-DAI isindependently applied to each CG, the counter-DAI (and/or total-DAI)related proposals of the present invention may be employed. Here, theCGs may be configured according to a specific criterion. For example,cell(s) having the same maximum number of transmittable TBs or cell(s)having the same carrier type (e.g., LCell or UCell) may be bundled intoa CG.

FIG. 20 illustrates a BS, a relay and a UE applicable to the presentinvention.

Referring to FIG. 20, a wireless communication system includes a BS 110and a UE 120. When the wireless communication system includes a relay,the BS or UE may be replaced by the relay.

The BS includes a processor 112, a memory 114, an RF unit 116. Theprocessor 112 may be configured to implement the procedures and/ormethods proposed by the present invention. The memory 114 is connectedto the processor 112 and stores information related to operations of theprocessor 112. The RF unit 116 is connected to the processor 112,transmits and/or receives an RF signal. The UE 120 includes a processor122, a memory 124, and an RF unit 126. The processor 112 may beconfigured to implement the procedures and/or methods proposed by thepresent invention. The memory 124 is connected to the processor 122 andstores information related to operations of the processor 122. The RFunit 126 is connected to the processor 122, transmits and/or receives anRF signal.

The aforementioned embodiments are achieved by combination of structuralelements and features of the present invention in a predeterminedfashion. Each of the structural elements or features should beconsidered selectively unless specified otherwise. Each of thestructural elements or features may be carried out without beingcombined with other structural elements or features. Also, somestructural elements and/or features may be combined with one another toconstitute the embodiments of the present invention. The order ofoperations described in the embodiments of the present invention may bechanged. Some structural elements or features of one embodiment may beincluded in another embodiment, or may be replaced with correspondingstructural elements or features of another embodiment. Moreover, it willbe apparent that some claims referring to specific claims may becombined with other claims referring to the other claims other than thespecific claims to constitute the embodiment or add new claims by meansof amendment after the application is filed.

The embodiments of the present invention have been described based ondata transmission and reception between a BS (or eNB) and a UE. Aspecific operation which has been described as being performed by the BSmay be performed by an upper node of the BS as the case may be. In otherwords, it will be apparent that various operations performed forcommunication with the UE in the network which includes a plurality ofnetwork nodes along with the BS may be performed by the BS or networknodes other than the BS. The BS may be replaced with terms such as fixedstation, Node B, eNode B (eNB), and access point. Also, the term UE maybe replaced with terms such as UE (MS) and mobile subscriber station(MSS).

The embodiments according to the present invention may be implemented byvarious means, for example, hardware, firmware, software, orcombinations thereof. If the embodiment according to the presentinvention is implemented by hardware, the embodiment of the presentinvention may be implemented by one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,microcontrollers, microprocessors, etc.

If the embodiment according to the present invention is implemented byfirmware or software, the embodiment of the present invention may beimplemented by a module, a procedure, or a function, which performsfunctions or operations as described above. Software code may be storedin a memory unit and then may be driven by a processor. The memory unitmay be located inside or outside the processor to transmit and receivedata to and from the processor through various well known means.

It will be apparent to those skilled in the art that the presentinvention may be embodied in other specific forms without departing fromthe spirit and essential characteristics of the invention. Thus, theabove embodiments are to be considered in all respects as illustrativeand not restrictive. The scope of the invention should be determined byreasonable interpretation of the appended claims and all change whichcomes within the equivalent scope of the invention are included in thescope of the invention.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a UE, BS or other devices of awireless mobile communication system. Specifically, the presentinvention is applicable to a method for transmitting uplink controlinformation and an apparatus for the same.

What is claimed is:
 1. A method for receiving a hybrid automatic repeatrequest (HARQ-ACK) payload by a base station in a carrier aggregation(CA) wireless communication system, the method comprising: transmittinga first physical downlink control channel (PDCCH) for downlinkscheduling through one of plural cells in a time interval, the firstPDCCH including a first downlink assignment index (DAI) and a secondDAI; transmitting a downlink data based on the first PDCCH; andreceiving the HARQ-ACK payload including HARQ-ACK information for thedownlink data generated by a user equipment (UE) based on the first andsecond DAIS, wherein the first DAI is related to a counter value of thedownlink scheduling, the counter value being counted in a cellprioritized manner in a unit of {cell, time interval} pair, and whereinthe second DAI indicates a total number of downlink scheduling(s) overthe plural cells, up to a current time interval within a set of timeintervals, the total number being updated from time interval to timeinterval, and the second DAI has a same value as other second DAIScorresponding to a plurality of first PDCCHs and received in a same timeinterval.
 2. The method according to claim 1, wherein the first PDCCH istransmitted in a UE-specific search space (USS) within the set of timeintervals.
 3. The method of claim 2, further comprising: transmitting asecond PDCCH in a common search space (CSS) within the set of timeintervals, wherein the second PDCCH does not contain the second DAI. 4.The method according to claim 1, wherein the first PDCCH is (i) a PDCCHfor scheduling a physical downlink shared channel (PDSCH) or (ii) aPDCCH indicating a semi-persistent scheduling release (SPS release). 5.The method according to claim 4, wherein the HARQ-ACK payload comprisesan HARQ-ACK response to the PDSCH or an HARQ-ACK response to the PDCCHindicating the SPS release.
 6. The method according to claim 1, whereinthe set of time intervals consists of SF #n-k, and an uplink (UL)subframe is a subframe #n, wherein K: {k₀, k₁, . . . K_(M−1)} is givenper cell as follows: TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 78 9 0 — — 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 —— — — 8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7,11 6, 5, 4, 7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, — — — — — — — 11,6 6 — — 7 7 5 — — 7 7  —.


7. The method according to claim 1, wherein the cell prioritized mannerincludes: downlink scheduling is counted in order of increasing timeinterval index after increasing a cell index within the set of timeintervals.
 8. The method according to claim 1, wherein the set of timeintervals includes a bundling window of downlink (DL) subframes.
 9. Abase station configured to receive a hybrid automatic repeat request(HARQ-ACK) payload in a carrier aggregation (CA) wireless communicationsystem, the base station comprising: a radio frequency (RF) unit; and aprocessor, wherein the processor is configured to: transmit a firstphysical downlink control channel (PDCCH) for downlink schedulingthrough one of plural cells in a time interval, the first PDCCHincluding a first downlink assignment index (DAI) and a second DAI;transmit a downlink data based on the first PDCCH; and receive theHARQ-ACK payload including HARQ-ACK information for the downlink datagenerated by a user equipment (UE) based on the first and second DAIs,wherein the first DAI is related to a counter value of the downlinkscheduling, the counter value being counted in a cell prioritized mannerin a unit of {cell, time interval} pair, and wherein the second DAI isrelated to a total number of downlink scheduling(s) over the pluralcells, up to a current time interval within a set of time intervals, thetotal number being updated from time interval to time interval, and thesecond DAI has a same value as other second DAIs corresponding to aplurality of first PDCCHs and received in a same time interval.
 10. Thebase station according to claim 9, wherein the first PDCCH istransmitted in a UE-specific search space (USS) within the set of timeintervals.
 11. The base station according to claim 10, wherein theprocessor is further configured to transmit a second PDCCH in a commonsearch space (CSS) within the set of time intervals, wherein the secondPDCCH does not contain the second DAI.
 12. The base station according toclaim 9, wherein the first PDCCH is (i) a PDCCH for scheduling aphysical downlink shared channel (PDSCH) or (ii) a PDCCH indicating asemi-persistent scheduling release (SPS release).
 13. The base stationaccording to claim 12, wherein the HARQ-ACK payload comprises anHARQ-ACK response to the PDSCH or an HARQ-ACK response to the PDCCHindicating the SPS release.
 14. The base station according to claim 9,wherein the set of time intervals consists of SF #n-k, and an uplink(UL) subframe is a subframe #n, wherein K: {k₀, k₁, . . . k_(M−1)} isgiven per cell as follows: TDD UL-DL Subframe n Configuration 0 1 2 3 45 6 7 8 9 0 — — 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7,4, 6 — — — — 8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12,8, 7, 11 6, 5, 4, 7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, — — — — — —— 11, 6 6 — — 7 7 5 — — 7 7  —.


15. The base station according to claim 9, wherein the cell prioritizedmanner includes: downlink scheduling is counted in order of increasingtime interval index after increasing a cell index within the set of timeintervals.
 16. The base station according to claim 9, wherein the set oftime intervals includes a bundling window of downlink (DL) subframes.